RISK FACTORS

Investing in our common stock involves a high degree of risk. You should carefully consider the following risks and all of the other information contained in this prospectus, including our consolidated financial statements and related notes, before investing in our common stock. While we believe that the risks and uncertainties described below are the material risks currently facing us, additional risks that we do not yet know of or that we currently think are immaterial may also arise and materially affect our business. If any of the following risks materialize, our business, financial condition and results of operations could be materially and adversely affected. In that case, the trading price of our common stock could decline, and you may lose some or all of your investment.

Risks Related to Our Business and Industry

Our success depends on growth in market acceptance of the human resources outsourcing and related services we provide.

Our success depends on the willingness of SMBs to outsource their HR function to a third-party service provider. Based on data published by the National Association of Professional Employer Organizations, we estimate that in 2012 fewer than 5% of U.S. employees of businesses with fewer than 500 employees were part of a co-employment arrangement, in which all or some portion of the employer’s HR function was outsourced to a single third-party provider such as TriNet. We believe that our growth opportunity is primarily a function of our ability to penetrate the SMB market. Many companies have invested substantial personnel, infrastructure and financial resources in their own internal HR organizations and therefore may be reluctant to switch to our solution. Companies may not engage us for other reasons, including a desire to maintain control over all aspects of their HR activities, a belief that they manage their HR activities more effectively using their internal administrative organizations, perceptions about the expenses associated with our services, perceptions about whether our services comply with laws and regulations applicable to them or their businesses, or other considerations that may not always be evident. Additional concerns or considerations may also emerge in the future. We must address our potential clients’ concerns and explain the benefits of our approach in order to convince them to change the way that they manage their HR activities, particularly in parts of the United States where our company and solution are less well-known. If we are not successful in addressing potential clients’ concerns and convincing companies that our solution can fulfill their HR needs, then the market for our solution may not develop as we anticipate and our business may not grow.

If we are unable to rapidly grow our sales force, we will not be able to grow our business at the rate that we anticipate, which could harm our business, results of operations and financial condition.

In order to raise awareness of the benefits of our services and identify and acquire new clients, we must rapidly grow our direct sales force, which consists of regional sales representatives who focus on serving clients in specific industry vertical markets. Competition for skilled sales personnel is intense, and we cannot assure you that we will be successful in attracting, training and retaining qualified sales personnel, or that our newly hired sales personnel will function effectively, either individually or as a group. In addition, our newly hired sales personnel are typically not productive for up to a year following their hiring. This results in increased near-term costs to us relative to the sales contributions of these newly hired sales personnel. If we are unable to rapidly grow and effectively train our sales force, our revenues likely will not increase at the rate that we anticipate, which could harm our business, results of operations and financial condition.

We are subject to client attrition.

We regularly experience significant client attrition due to a variety of factors, including increases in administrative fees and insurance costs, disruption caused by the transition of WSEs we have gained through acquisition to our technology platform, client business failure, competition and clients determining to bring HR administration in-house. Our standard client service agreement can be cancelled by us or by the client without penalty with 30 days’ prior written notice. Clients who intend to cease doing business with us often elect to do so effective as of the beginning of a calendar year. As a result, in the first quarter of each year we experience our

14

Table of Contents

largest concentration of client attrition. In addition, we experience higher levels of client attrition in connection with renewals of the health insurance we provide for WSEs in the event that such renewals result in increased premiums that we pass on to our clients. If we were to experience client attrition in excess of our planned annual attrition rate of approximately 20% of our installed WSE base, as we did in 2010 and 2011, it could harm our business, results of operations and financial condition.

Our acquisition strategy creates risks for our business.

We have completed numerous acquisitions of other businesses, and we expect that we will continue to grow through acquisitions of other businesses, assets or technologies. We may fail to identify attractive acquisition candidates or we may be unable to reach acceptable terms for future acquisitions. If we are unable to complete acquisitions in the future, our ability to grow our business will be impaired.

We may pay for acquisitions by issuing additional shares of our common stock, which would dilute our stockholders, or by issuing debt, which could include terms that restrict our ability to operate our business or pursue other opportunities and subject us to meaningful debt service obligations. We may also use significant amounts of cash to complete acquisitions. To the extent that we complete acquisitions in the future, we likely will incur future depreciation and amortization expenses associated with the acquired assets. We may also record significant amounts of intangible assets, including goodwill, which could become impaired in the future. Acquisitions involve numerous other risks, including:

If we fail to integrate newly acquired businesses effectively, we might not achieve the growth, service enhancement or operational efficiency objectives of the acquisitions, and our business, results of operations and financial condition could be harmed.

Unexpected changes in workers compensation and health insurance claims by worksite employees could harm our business.

Our insurance costs are impacted significantly by our WSEs’ health and workers compensation insurance claims experience. We establish reserves to provide for the estimated costs of reimbursing our workers

15

Table of Contents

compensation and health insurance carriers for paying claims within the deductible layer in accordance with their insurance policies. Estimating these reserves involves our consideration of a number of factors and requires significant judgment. If there is an unexpected increase in the severity or frequency of claims, such as due to our WSEs generating additional claims activity, or if we subsequently receive updated information indicating insurance claims were higher than previously estimated and reported, our insurance costs could be higher in that period or subsequent periods as we adjust our reserves accordingly. In addition, we may be unable to increase our pricing to offset increases in insurance costs on a timely basis. A number of factors affect claim activity levels, such as changes in general economic conditions, proposed and enacted regulatory changes and disease outbreaks.

Our quarterly results of operations may fluctuate as a result of numerous factors, many of which are outside of our control.

Our quarterly results of operations are likely to fluctuate, and our results in some quarters may be below the expectations of research analysts and our investors, which could cause the price of our common stock to decline. Some of our significant expenses, such as insurance costs for our WSEs, rent expense and debt expense, may require significant lead time to reduce. If we do not achieve our expected revenues targets, we may be unable to adjust our costs quickly enough to offset any revenues shortfall, which could harm our results of operations. Some of the important factors that may cause our revenues, results of operations and cash flows to fluctuate from quarter to quarter include:

Many of the above factors are discussed in more detail elsewhere in this “Risk Factors” section and in the sections titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and “Business.” Many of these factors are outside our control, and the variability and unpredictability of these factors could cause us to fail to meet our expectations for revenues or results of operations for a given period. In addition, the occurrence of one or more of these factors might cause our results of operations to vary widely, which could lead to negative impacts on our margins, short-term liquidity or ability to retain or attract key personnel, and could cause other unanticipated issues. Accordingly, we believe that quarter-to-quarter comparisons of our revenues, results of operations and cash flows may not be meaningful and should not be relied upon as an indication of our future performance.

16

Table of Contents

Our business is subject to numerous state and federal laws, and uncertainty as to the application of these laws, or adverse applications of these laws, as well as changes in applicable laws, could adversely affect our business.

Our operations are governed by numerous federal, state and local laws relating to labor, tax, benefits, insurance and employment matters. We are a professional employer organization, and by entering into a co-employer relationship with WSEs, we assume certain obligations, responsibilities and potential legal risks of an employer under these laws. However, many of these laws (such as the Employee Retirement Income Security Act, or ERISA, and federal and state employment tax laws) do not specifically address the obligations and responsibilities of a provider of outsourced HR in a co-employer relationship, and the definition of employer under these laws is not uniform. In addition, many states have not addressed the co-employer relationship for purposes of compliance with applicable state laws governing the relationship between employers and employees and state insurance laws. There is even greater uncertainty on the federal level, such as the application of immigration reform to a co-employer relationship, and tax credits for small businesses that utilize a co-employer relationship.

We are not able to predict whether broader federal or state regulation governing the co-employer relationship will be implemented, or if it is, how it will affect us. Any adverse application or interpretation (in courts, agencies or otherwise) of new or existing federal or state laws to the co-employer relationship with our WSEs and clients could harm our business. If federal, state or local jurisdictions were to change their regulatory framework related to outsourced HR, or introduce new laws governing our industry that were materially different from existing laws, those changes could reduce or eliminate the need for some of our services, or could require that we make significant changes in our methods of doing business, which could increase our cost of doing business. Changes in regulations could also affect the extent and type of benefits employers can or must provide employees, the amount and type of taxes employers and employees are required to pay or the time within which employers must remit taxes to the applicable authority. These changes could substantially decrease our revenues and substantially increase our cost of doing business. If we fail to educate and assist our clients regarding new or revised legislation that impacts them, our reputation could be harmed.

Although some states do not explicitly regulate professional employer organizations, 42 states have passed laws that have licensing, certification or registration requirements applicable to professional employer organizations or recognize the professional employer organization model, and other states may implement such requirements in the future. Laws regulating professional employer organizations vary from state to state, but generally provide for oversight of the fiscal responsibility of professional employer organizations, and in some cases codify and clarify the co-employment relationship for processing unemployment claims, workers compensation and other purposes under state law. We may be required to spend significant time and resources to satisfy licensing requirements or other applicable regulations in some states, and we may not be able to satisfy these requirements or regulations in all states, which could prohibit us from doing business in such states. In addition, we cannot assure you that we will be able to renew our licenses in all states.

If we are not recognized as an employer of worksite employees under federal and state regulations, we and our clients could be adversely impacted.

In order for WSEs to receive the full benefit of our benefits offerings, it is important that we act and qualify as an employer of the WSEs under the Internal Revenue Code of 1986, or the Code, and ERISA. In addition, our status as an employer is important for purposes of ERISA preemption of state laws. The definition of employer under various laws is not uniform, and under both the Code and ERISA the term is defined in part by complex multi-factor tests under common law. We believe that we qualify as an employer of our WSEs in the United States under both the Code and ERISA, and we implement processes to protect and preserve this status. However, the U.S. Department of Labor has issued guidance that certain entities in the HR outsourcing industry do not qualify as common law employers of WSEs for ERISA purposes. If we were found not to be an employer under the Code, our WSEs may not receive the favorable tax treatment for any plans intended to qualify under Section 401 of the Code, including our 401(k) plans and cafeteria plans, which could have a material adverse effect on our business. If we were found not to be an employer for ERISA purposes, our plans would not comply with ERISA, and fines and penalties could be imposed. In addition, if we were found not to be an employer for

17

Table of Contents

ERISA purposes, we and our plans would not enjoy the full preemption of state laws provided by ERISA and could be subject to varying state laws and regulations, including laws governing multiple employer welfare arrangements, or MEWAs, as well as to claims based upon state laws.

We and our clients could be adversely impacted by health care reform.

The Patient Protection and Affordable Care Act and the Heath Care and Education Reconciliation Act of 2010, which we refer to collectively as the Act, entail sweeping health care reforms with staggered effective dates from 2010 through 2018, and many provisions of the Act require the issuance of additional guidance from the U.S. Departments of Labor and Health and Human Services, the Internal Revenue Service, and U.S. states. Beginning in 2014, a number of key provisions of the Act take effect, including the establishment of state insurance exchanges, insurance market reforms, “pay or play” penalties on large employers and the imposition of excise taxes on the health insurance industry and reinsurance taxes on insurers and third-party administrators. Collectively, these items have the potential to significantly change the insurance marketplace for employers and how employers provide insurance to employees.

As a co-employer of our clients’ WSEs, we assume or share many of the employer-related responsibilities and legal risks and assist our clients in complying with many employment-related governmental regulations. Generally, the Act and subsequently issued guidance by the Internal Revenue Service and the U.S. Department of Health and Human Services have not addressed, or in some instances are unclear, as to their application in the co-employment relationship. For example, the Act provides for a small business tax credit for eligible companies offering health care coverage to employees. We believe that these tax credits are available to our clients that meet the qualification requirements; however, the Act and subsequently issued Internal Revenue Service guidance do not expressly address the issue of whether small business clients of a professional employer organization may still qualify as small business eligible for such tax credits. As a result of this uncertainty, we are not yet able to determine the impacts to our business, and to our clients, resulting from the Act. In future periods, the changes may result in increased costs to us and our clients and could affect our ability to attract and retain clients. Additionally, we may be limited or delayed in our ability to increase service fees to offset any associated potential increased costs resulting from compliance with the Act. Furthermore, the uncertainty surrounding the terms and application of the Act may delay or inhibit the decisions of potential clients to outsource their HR needs. Any of these developments could harm our business, results of operations and financial condition.

We may have additional tax liabilities, which could harm our business, operating results, financial condition and prospects.

Significant judgments and estimates are required in determining our provision for income taxes and other tax liabilities. Our provision for income taxes, results of operations and cash flows may be impacted if any of our tax positions are challenged and successfully disputed by the tax authorities. In determining the adequacy of our tax provision, we assess the likelihood of adverse outcomes that could result if our tax positions were challenged by the Internal Revenue Service, or IRS, and other tax authorities. The tax authorities in the United States regularly examine our income and other tax returns. For example, in connection with an IRS examination of prior federal income tax returns filed by Gevity, a company we acquired in 2009, we recently received a technical advice memorandum from the IRS taking the position that approximately $10.1 million of tax credits taken by Gevity, and an additional approximately $2.0 million taken by us after acquiring Gevity, should be reversed, which position we dispute. The ultimate outcome of these examinations and tax disputes cannot be predicted with certainty. Should the IRS or other tax authorities assess additional taxes as a result of examinations, we may be required to record charges to operations that could have a material impact on our results of operations, financial position or cash flows.

Our business and operations have experienced rapid growth in recent periods, and if we are unable to effectively manage this growth, our business and results of operations may suffer.

We have experienced rapid growth and have significantly expanded our operations in recent periods, which has placed a strain on our management, administrative, operational and financial infrastructure. Managing this growth requires us to further refine our operational, financial and management controls and reporting systems and procedures.

18

Table of Contents

Our ability to effectively manage any significant growth of our business will depend on a number of factors, including our ability to do the following:

These activities will require significant operating and capital expenditures and allocation of valuable management and employee resources, and we expect that our growth will continue to place significant demands on our management and on our operational and financial infrastructure.

Our future financial performance and our ability to execute on our business plan will depend, in part, on our ability to effectively manage any future growth. We cannot assure you that we will be able to do so in an efficient or timely manner, or at all. In particular, any failure to successfully implement systems enhancements and improvements will likely negatively impact our ability to manage our expected growth, ensure uninterrupted operation of key business systems and comply with the rules and regulations that are applicable to public companies. If we fail to manage our growth effectively, our costs and expenses may increase more than we expect them to, which in turn could harm our business, results of operations and financial condition.

We may not be able to sustain our revenue growth rate or profitability in the future.

While we have achieved profitability on an annual basis in each of the last two and four of the last five fiscal years, we expect our operating expenses to increase substantially in the near term, particularly as we make significant investments in our sales and marketing organization, expand our operations and infrastructure and enhance the breadth and quality of our services. If our revenues do not increase to offset these increases in our operating expenses, we may not be profitable in future periods.

Moreover, you should not consider our historical revenue growth to be indicative of our future performance. As we grow our business, our revenue growth rates may slow in future periods due to a number of reasons, which may include slowing demand for our services, increasing competition, a decrease in the growth of our overall market, our failure, for any reason, to continue to capitalize on growth opportunities, the maturation of our business or the decline in the number of SMBs in our target markets.

Our industry is highly competitive, which may limit our ability to maintain or increase our market share or improve our results of operations.

We face significant competition on a national and regional level from a number of companies purporting to deliver a range of bundled services that are generally similar to the services we provide, including large professional employer organizations such as the TotalSource unit of Automatic Data Processing, Inc. and Insperity, Inc., as well as specialized and small professional employer organization service providers. If and to the extent that we and other companies providing these services are successful in growing our businesses, we anticipate that future competitors will enter this industry. Some of our current, and any future, competitors have or may have greater marketing and financial resources than we do, and may be better positioned than we are in certain markets. Increased competition in our industry could result in price reductions or loss of market share, any of which could harm our business. We expect that we will continue to experience competitive pricing pressure. If we cannot compete effectively, our market share, business, results of operations and financial condition may suffer.

19

Table of Contents

In addition to competition from other professional employer organizations, we also face competition in the form of companies and third parties serving HR needs in traditional manners. These forms of competition include:

We believe that our services are attractive to many SMBs in part because of our ability to provide workers compensation, health care and other benefits programs to them on a cost-effective basis. We compete with insurance brokers and other providers of this coverage in this regard, and our offerings must be priced competitively with those provided by these competitors in order for us to attract and retain our clients.

We may not be successful in convincing potential clients that the use of our services is a superior, cost- effective means of satisfying their HR obligations relative to the way in which they currently satisfy these obligations.

If we cannot compete effectively against other professional employer organizations or against the alternative means by which companies meet their HR obligations, our market share, business, results of operations and financial condition may suffer.

Adverse changes in our relationships with key vendors could impair the quality of our solution.

Our success depends in part on our ability to establish and maintain arrangements and relationships with vendors that supply us with essential components of our services. These service providers include insurance carriers to provide health and workers compensation insurance coverage for WSEs, as well as other vendors such as couriers used to deliver client payroll checks and banks used to electronically transfer funds from clients to their employees. Failure by these service providers, for any reason, to deliver their services in a timely manner could result in material interruptions to our operations, impact client relations, and result in significant penalties or other liabilities to us. Our agreements with these service providers typically have a term of one year. In addition, many of our employee benefit plan agreements may be terminated by the insurance companies on 90 days’ notice. If any of these vendors decided to terminate its relationship with us, we may have difficulty obtaining replacement services at reasonable rates or on a timely basis, if at all. The loss of any one or more of our key vendors, or our inability to partner with certain vendors that are better-known or more desirable to our clients or potential clients, could impair the quality of our solution and harm our business.

We depend on licenses to third-party software in order to provide our services.

We license a substantial portion of the software on which we depend to provide services to our clients from third-party vendors, including Oracle America, Inc. If we are unable to maintain these licenses, or if we are required to make significant changes in the terms and conditions of these licenses, we may need to seek replacement vendors or change our software architecture to address licensing revisions with our current vendors, either of which could increase our expenses and impair the quality of our services. In addition, we cannot assure you that our key vendors will continue to support their technology. Financial or other difficulties experienced by these vendors may adversely affect the technologies we incorporate into our products and services. If this software ceases to be available, we may be unable to find suitable alternatives on reasonable terms, or at all.

If we are deemed to be an insurance agent or third-party administrator, we may incur significant additional costs and expenses, which could harm our results of operations.

State regulatory authorities generally require licenses for companies that do business in their states as insurance agents or third-party administrators, such as those that handle health or retirement plan funding and

20

Table of Contents

claim processing. Insurance and third-party administrator regulation covers a host of activities, including sales, underwriting, rating, claims payments and record keeping by companies and agents. We do not believe that our services constitute acting as an insurance agent or third-party administrator. If regulatory authorities in any state determine that the nature of our business requires that we be licensed as an insurance agent or as a third-party administrator, we may need to hire additional personnel to manage regulatory compliance and become obligated to pay annual regulatory fees, which could adversely affect our results of operations.

Most of our clients are concentrated in a relatively small number of industries, making us vulnerable to downturns in those industries.

Most of our clients operate in the technology, life sciences, property management, professional services, banking and financial services, retail, manufacturing and hospitality services industries. As a result, if any of those industries suffers a downturn, the portion of our business attributable to clients in that industry could be adversely affected. For example, in July 2013, we acquired Ambrose Employer Group, LLC, a New York-based company that provides HR services primarily to WSEs in the financial services industry in the New York area, which we refer to as Ambrose. If the financial services industry were to suffer a downturn similar to the one that began in the fall of 2008, our Ambrose product line would likely suffer.

We have a substantial amount of indebtedness, which could adversely affect our financial condition and our operating flexibility.

As of September 30, 2013, we had $820.0 million in outstanding indebtedness under our credit facility, all of which was secured indebtedness of our subsidiary, TriNet HR Corporation, guaranteed on a senior secured basis by us and certain of our subsidiaries. In August 2013, we entered into two new credit facilities, the proceeds of which we used to repay approximately $448.3 million of indebtedness outstanding under the previous credit facility, declare a special dividend, issue letters of credit and pay transaction costs. Our level of indebtedness and the limitations imposed on us by our credit facilities could affect our business in various ways, including the following:

Because borrowings under each of our credit facilities bear interest at variable rates, our interest expense could increase even though the amount borrowed remains the same, exacerbating these risks. Our ability to meet these expenses depends on our future business performance, which will be affected by various factors, including the risks described in this “Risk Factors” section. We are not able to control many of these factors, such as economic conditions in the markets where we operate and pressure from competitors. Our operations may provide insufficient cash to pay the principal and interest on our credit facility and to meet our other debt obligations. If so, we may be required to refinance all or part of our existing indebtedness or borrow additional funds, which we may not be able to do on terms that are acceptable to us, if at all. In addition, the terms of our existing or future debt agreements may restrict our ability to take some or all of these responsive actions. If we were unable to pay the principal and interest on our credit facility or meet our other debt obligations, the lenders under our credit facility could terminate their commitments to extend further credit to us and accelerate a substantial part of our indebtedness. If that were to happen, we may not be able to repay all of the amounts that would become due under our indebtedness or refinance our debt. If we were unable to repay those amounts or refinance our debt, the lenders under each of our credit

21

Table of Contents

facilities could proceed against the collateral granted to them to secure that indebtedness. If that were to happen, our results of operations and financial condition could be harmed and we might be forced to seek bankruptcy protection.

The terms of our credit facilities may restrict our current and future operations, which would impair our ability to respond to changes in our business and to manage our business.

Our credit facilities contain, and any future indebtedness of ours would likely contain, a number of restrictive covenants that impose significant operating and financial restrictions on us, including restricting our ability to:

Under the revolving credit facility, we are required to comply with a financial covenant that requires us and our subsidiaries to maintain a maximum leverage ratio so long as there is any indebtedness outstanding under the revolving credit facility (excluding letters of credit issued and outstanding of up to $15.0 million other than letters of credit that have been cash collateralized). Our ability to meet the leverage ratio can be affected by events beyond our control, and we may be unable to comply with it. Our failure to comply with this financial covenant or other restrictive covenants under our credit facilities and other debt instruments could result in a default under each of our credit facilities and/or other debt instruments, which in turn could result in the termination of the lenders’ commitments to extend further credit to us under our revolving credit facility and acceleration of a substantial portion of our indebtedness then outstanding under each of our credit facilities. If that were to happen, we may not be able to repay all of the amounts that would become due under our indebtedness or refinance our debt. If we were unable to repay those amounts or refinance our debt, the lenders under either of our credit facilities could proceed against the collateral granted to them to secure that indebtedness. If that were to happen, our results of operations and financial condition could be harmed and we might be forced to seek bankruptcy protection.

Volatility in the financial and economic environment could harm our business.

Demand for our services is sensitive to changes in the level of overall economic activity in the markets in which we operate. During periods of weak economic conditions, employment levels tend to decrease, small business failures tend to increase and interest rates may become more volatile. Current or potential clients may also react to weak economic conditions or forecasted weak economic conditions by reducing their employee headcount or by lowering their wage, bonus or benefits levels, any of which would affect our revenues, and may affect our margins, because we may be unable to reduce our selling, administrative or other expenses sufficient to offset the drop in revenues. It is difficult for us to forecast future demand for our services due to the inherent difficulty in

22

Table of Contents

forecasting the direction and strength of economic cycles. These conditions may affect the willingness of our clients and potential clients to pay outside vendors for services like ours, and may impact their ability to pay their obligations to us on time, or at all. In addition, if businesses have difficulty obtaining credit, business growth and new business formation may be impaired, which could also harm our business. Even modest downturns in economic activity or the availability of credit on a regional or national level could harm our business.

If we fail to retain our key personnel or fail to attract additional skilled personnel, our business may suffer.

Our operations are dependent on the continued efforts of our officers and executive management and the performance and productivity of our regional managers and field personnel. Our ability to attract and retain business depends on the quality of our services and the relationships that we maintain with our clients. If we lose key personnel with significant experience in managing our business, this could impair our ability to deliver services effectively or profitably, could divert other senior management time in seeking replacements, and could adversely affect our reputation with our clients and potential clients. Some of our most important client relationships depend on the continued involvement of individual managers or sales personnel, and any loss of those individuals could jeopardize those relationships and in turn adversely affect our operating results.

Our future success will depend on our ability to attract, hire, train and retain highly skilled technical, sales and marketing and support personnel, particularly with expertise in outsourced solutions and the technology platforms that we deploy today and will deploy in the future. Qualified personnel are in great demand throughout the HR industry. Our failure to attract and retain the appropriate personnel may limit the rate at which we can expand our business, including developing new services and attracting new clients.

Improper disclosure of sensitive or confidential company, employee or client data, including personal data, could result in liability and harm our reputation.

Our business involves the use, storage and transmission of information about our corporate employees, WSEs and clients. This information includes sensitive or confidential data, such as employees’ Social Security numbers, bank account numbers, retirement account information and medical information. We and our third-party service providers have established policies and procedures to help protect the security and privacy of this information, but it is possible that our security controls over sensitive or confidential data may not prevent the improper access to or disclosure of this information. Third parties, including vendors that provide services for our operations, could also be a source of security risk to us in the event of a failure of their own security systems and infrastructure. Any such disclosure could harm our reputation and expose us to liability under our contracts and under the many and sometimes contradictory laws and regulations regarding data privacy in the various markets in which we operate. Any failure to adhere to applicable laws and regulations or to our contractual commitments with respect to the preservation and use of confidential information could result in legal liability and could damage our reputation.

Any failure in our business systems could reduce the quality of our business services, which could harm our reputation and expose us to liability.

Our business systems rely on the complex integration of numerous hardware and software subsystems to manage the transactions involved in managing the client relationship through the processing of employee, payroll and benefits data. These systems can be disrupted by, among other things, equipment failures, computer server or systems failures, network outages, malicious acts, software errors or defects, vendor performance problems and power failures. Any delay or failure in our systems that impairs our ability to communicate electronically with our clients, employees or vendors or our ability to store or process data could harm our reputation and our business. If we are unable to meet client demands or service expectations, we may lose existing clients and we may have difficulty attracting new clients. In addition, errors in our products and services, such as the erroneous denial of healthcare benefits or delays in making payroll, could expose our clients to liability claims from improperly serviced WSEs, for which we are contractually obligated to provide indemnification.

23

Table of Contents

We have disaster recovery, business continuity, and crisis management plans and procedures designed to protect our business against a multitude of events, including natural disasters, military or terrorist actions, power or communication failures, or similar events. Despite our preparations, our plans may not be successful in preventing the loss of client data, service interruptions, and disruptions to our operations, or damage to our important facilities. The precautions that we have taken to protect ourselves against these types of events may prove to be inadequate. If we suffer damage to our data or operations centers, experience a telecommunications failure or experience a security breach, our operations could be interrupted. Any interruption or other loss may not be covered by our insurance and could harm our reputation.

If our systems were to fail for any of these reasons during payroll processing, preventing the proper payment of employees, or the proper remission of payroll taxes, we could be liable for wage payment delay penalties and payroll tax penalties, as well as other contractual penalties. Any inaccuracies in the processing of health insurance benefits could result in our being liable for lapses in insurance. If any of our systems fails to operate properly or becomes disabled even for a brief period of time, we could suffer financial loss, a disruption of our businesses, liability to clients, regulatory intervention, or damage to our reputation.

We must keep pace with rapid technological change in order to succeed.

Our business depends upon the use of software, hardware and networking technologies that must be frequently and rapidly upgraded in response to technological advances, competitive pressures and consumer expectations. To succeed, we will need to effectively develop or license and integrate these new technologies as they become available to improve our services commensurate with client requirements. In particular, we rely on enterprise software applications licensed from third parties that are upgraded from time to time, such as PeopleSoft HR information systems and Oracle databases, that provide the basis for our HR information system platform supporting payroll, benefits and other HR functions. Any difficulties we encounter in adapting applications upgrades to our systems could harm our performance or delay or prevent the successful development, introduction or marketing of new services. New products or upgrades may not be released according to schedule, or may contain defects when released. Difficulties in integrating new technologies could result in adverse publicity, loss of sales, delay in market acceptance of our services, or client claims against us, any of which could harm our business. We could also incur substantial costs in modifying our services or infrastructure to adapt to these changes. In addition, we could lose market share if our competitors develop technologically superior products and services.

Our co-employment relationship with our worksite employees exposes us to business risks.

We are a co-employer of our WSEs, and there is a possibility that we may be subject to liability for violations of employment laws by our clients and acts or omissions of our WSEs, who may be deemed to be our agents, even if we do not participate in any such acts or violations. Such laws include, but are not limited to, laws relating to payment of wages, employment discrimination, labor relations and whistleblower protection. Although our client agreements establish the contractual division of responsibilities between us and our clients for various personnel management matters, including compliance with and liability under various governmental regulations, as well as providing for clients to indemnify us for any liability attributable to clients’ or their employees’ conduct, we may not be able to effectively enforce or collect these contractual obligations with our clients, which could harm our business. We maintain employment practices liability insurance coverage (including coverages for our clients) to manage our and our clients’ exposure for various employee-related claims, and as a result, our incurred costs with respect to this exposure have historically been insignificant to our operating results. Employment practices liability insurance generally excludes coverage for claims relating to compliance with laws associated with the classification of employees as exempt or non-exempt, such as overtime pay and minimum wage law compliance. We cannot assure you that our insurance will be sufficient in amount or scope to cover all claims that may be asserted against us and for which we are unable to obtain indemnification from our clients. If judgments or settlements related to WSEs that we and our clients employ exceed our insurance coverage, it could harm our results of operations and financial condition. We cannot assure you that we will be able to obtain appropriate types and levels of insurance in the future, that we will be able to replace existing policies on acceptable terms, or at all, or that our insurers will be able to pay all claims that we may make under our policies, any of which could harm our business.

24

Table of Contents

Our failure to maintain or enhance our reputation or brand recognition could harm our business.

We believe that maintaining and enhancing our reputation and the TriNet brand identity is critical to maintaining our relationships with our clients and vendors and our ability to attract new clients and vendors. We also believe that our reputation and brand identity will become more important as competition in our industry continues to develop. Our ability to maintain and enhance our reputation and brand identity will be affected by a number of factors, some of which are beyond our control, including:

Any brand promotion activities in which we engage may not be successful or yield increased revenues. Furthermore, negative publicity, whether or not justified, relating to events or activities attributed to us, our corporate employees, our WSEs, our vendors, other companies in our industry or others associated with any of these parties, may tarnish our reputation and reduce the value of our brand. Damage to our reputation and loss of brand equity may reduce demand for our services and harm our business, results of operations and financial condition. Moreover, any attempts to rebuild our reputation and restore the value of our brand may be costly and time-consuming, and any such efforts may not ultimately be successful.

If we are unable to protect our intellectual property, or if we infringe on the intellectual property rights of others, our business may be harmed.

Our success depends in part on intellectual property rights to the services that we develop. We rely on a combination of contractual rights, including non-disclosure agreements, trade secrets, copyrights and trademarks, to establish and protect our intellectual property rights in our names, services, methodologies and related technologies. If we lose intellectual property protection or the ability to secure intellectual property protection on any of our names, confidential information or technology, this could harm our business. Our intellectual property rights may not prevent competitors from independently developing services and methodologies similar to ours, and the steps we take might be inadequate to deter infringement or misappropriation of our intellectual property by competitors, former employees or other third parties, any of which could harm our business. We do not currently have any registered patents or pending patent applications covering any of our technology. We own registered trademarks in the United States and Canada that have various expiration dates unless renewed through customary processes. Our trademark registrations may be unenforceable or ineffective in protecting our trademarks. Our trademarks may be unenforceable in countries outside of the United States, which may adversely affect our ability to build our brand outside of the United States.

Although we believe that our conduct of our business does not infringe on the intellectual property rights of others, third parties may nevertheless assert infringement claims against us in the future. We may be required to modify our products, services, internal systems or technologies, or obtain a license to permit our continued use of those rights. We may be unable to do so in a timely manner, or upon reasonable terms and conditions, which could harm our business. In addition, future litigation over these matters could result in substantial costs and resource diversion. Adverse determinations in any litigation or proceedings of this type could subject us to significant liabilities to third parties and could prevent us from using some of our services, internal systems or technologies.

25

Table of Contents

Our use of open source software could subject us to possible litigation.

A portion of our technologies incorporates open source software, and we expect to continue to incorporate open source software into our platform in the future. Few of the licenses applicable to open source software have been interpreted by courts, and their application to the open source software integrated into our proprietary technology platform may be uncertain. If we fail to comply with these licenses, then pursuant to the terms of these licenses, we may be subject to certain requirements, including requirements that we make available the source code for our software that incorporates the open source software. We cannot assure you that we have not incorporated open source software in our software in a manner that is inconsistent with the terms of the applicable licenses or our current policies and procedures. If an author or other third party that distributes such open source software were to allege that we had not complied with the conditions of one or more of these licenses, we could incur significant legal expenses defending against such allegations. Litigation could be costly for us to defend, have a negative effect on our operating results and financial condition or require us to devote additional research and development resources to change our technology platform.

If we are unable to implement and maintain effective internal control over financial reporting in the future, investors may lose confidence in the accuracy and completeness of our financial reports and the market price of our common stock may be negatively affected.

As a public company, we will be required to maintain internal control over financial reporting and to report any material weaknesses in such internal controls. Section 404 of the Sarbanes-Oxley Act requires that we evaluate and determine the effectiveness of our internal control over financial reporting and, beginning with our annual report for the year ending December 31, 2015, provide a management report on our internal control over financial reporting. This report must be attested to by our independent registered public accounting firm. If we have a material weakness in our internal control over financial reporting, we may not detect errors on a timely basis and our financial statements may be materially misstated.

We are in the process of designing and implementing our internal control over financial reporting, which process will be time consuming, costly and complicated. If we identify material weaknesses in our internal control over financial reporting in the future, we are unable to comply with the requirements of Section 404 in a timely manner, we are unable to assert that our internal control over financial reporting is effective or our independent registered public accounting firm is unable to express an opinion as to the effectiveness of our internal control over financial reporting when required to do so, investors may lose confidence in the accuracy and completeness of our financial reports and the market price of our common stock could be negatively affected, and we could become subject to investigations by the stock exchange on which our securities are listed, the Securities and Exchange Commission, or SEC, or other regulatory authorities, which could require additional financial and management resources.

If we are unable to successfully remediate the existing material weakness in our internal control over financial reporting, the accuracy and timing of our financial reporting may be adversely affected.

In preparing and reviewing our consolidated financial statements as of and for the nine months ended September 30, 2013, we and our independent registered public accounting firm identified a material weakness in our internal control over financial reporting. A material weakness is a deficiency, or a combination of deficiencies, in internal control over financial reporting such that there is a reasonable possibility that a material misstatement of our financial statements will not be prevented or detected on a timely basis. The material weakness identified related to our incorrectly recording a deferred tax asset in connection with our accounting for our acquisition of Ambrose that should have been reported as goodwill. As a result, there were adjustments required in connection with closing our books and records and preparing our consolidated financial statements for the nine months ended September 30, 2013.

In response to this material weakness, we plan to hire additional personnel to build our financial management and reporting infrastructure, and further develop and document our accounting policies and financial reporting procedures. However, we cannot assure you that we will be successful in pursuing these

26

Table of Contents

measures or that these measures will significantly improve or remediate the material weakness described above. We also cannot assure you that we have identified all of our existing material weaknesses, or that we will not in the future have additional material weaknesses.

Neither we nor our independent registered public accounting firm has performed an evaluation of our internal control over financial reporting during any period in accordance with the provisions of the Sarbanes-Oxley Act. In light of the material weakness that was identified as a result of the limited procedures performed, we believe that it is possible that, had we and our independent registered public accounting firm performed an evaluation of our internal control over financial reporting in accordance with the provisions of the Sarbanes-Oxley Act, additional material weaknesses or significant control deficiencies may have been identified.

If we fail to remediate the material weakness or to meet the demands that will be placed upon us as a public company, including the requirements of the Sarbanes-Oxley Act, we may be unable to accurately report our financial results, or report them within the timeframes required by law or stock exchange regulations. Failure to comply with Section 404 of the Sarbanes-Oxley Act could also potentially subject us to sanctions or investigations by the SEC or other regulatory authorities. We cannot assure you that we will be able to remediate the material weakness in a timely manner, or at all, or that in the future, additional material weaknesses will not exist or otherwise be discovered. If our efforts to remediate the material weakness identified are not successful, or if other material weaknesses or other significant control deficiencies occur, our ability to accurately and timely report our financial results could be impaired, which could result in late filings of our annual and quarterly reports under the Securities Exchange Act of 1934, as amended, or the Exchange Act, restatements of our consolidated financial statements, a decline in our stock price, suspension or delisting of our common stock from the                     , and could adversely affect our reputation, results of operations and financial condition.

We will incur substantial increased costs as a result of being a public company.

As a public company, we will incur significant levels of legal, accounting and other expenses that we did not incur as a private company. We will be subject to the reporting requirements of the Exchange Act, the Sarbanes-Oxley Act, the Dodd-Frank Act, the listing requirements of                      and other applicable securities rules and regulations. Compliance with these rules and regulations will increase our legal and financial compliance costs, make some activities more difficult, time-consuming or costly and increase demand on our systems and resources. The Exchange Act requires, among other things, that we file annual, quarterly and current reports with respect to our business and results of operations. The Sarbanes-Oxley Act requires, among other things, that we maintain effective disclosure controls and procedures and internal control over financial reporting. In order to maintain and, if required, improve our disclosure controls and procedures and internal control over financial reporting to meet this standard, significant resources and management oversight may be required. As a result, management’s attention may be diverted from other business concerns, which could adversely affect our business and results of operations. Although we have already hired additional corporate employees to comply with these requirements, we may need to hire more corporate employees in the future or engage outside consultants, which would increase our costs and expenses.

In addition, changing laws, regulations and standards relating to corporate governance and public disclosure are creating uncertainty for public companies, increasing legal and financial compliance costs and making some activities more time-consuming. These laws, regulations and standards are subject to varying interpretations, in many cases due to their lack of specificity, and, as a result, their application in practice may evolve over time as new guidance is provided by regulatory and governing bodies. This could result in continuing uncertainty regarding compliance matters and higher costs necessitated by ongoing revisions to disclosure and governance practices. We intend to invest resources to comply with evolving laws, regulations and standards, and this investment may result in increased general and administrative expenses and a diversion of management’s time and attention from revenue-generating activities to compliance activities. If our efforts to comply with new laws, regulations and standards differ from the activities intended by regulatory or governing bodies due to ambiguities related to their application and practice, regulatory authorities may initiate legal proceedings against us and our business may be adversely affected.

27

Table of Contents

We also expect that being a public company and these new rules and regulations will make it more expensive for us to obtain director and officer liability insurance, and we may be required to accept reduced coverage or incur substantially higher costs to obtain coverage. These factors could also make it more difficult for us to attract and retain qualified members of our board of directors, particularly to serve on our audit committee and compensation committee, and qualified executive officers.

As a result of disclosure of information in this prospectus and in the filings that we will be required to make as a public company, our business, results of operations and financial condition will become more visible, which may result in threatened or actual litigation, including by competitors and other third parties. If any such claims are successful, our business, results of operations and financial condition could be adversely affected, and even if the claims do not result in litigation or are resolved in our favor, these claims, and the time and resources necessary to resolve them, could divert the resources of our management and adversely affect our business, results of operations and financial condition.

Risks Related to This Offering and Ownership of Our Common Stock

There has been no prior market for our common stock. An active market for our common stock may not develop or be sustainable and investors may not be able to resell their shares at or above the initial public offering price.

There has been no public market for our common stock prior to this offering. The initial public offering price for our common stock will be determined through negotiations between the representatives of the underwriters and us and may vary from the market price of our common stock following this offering. If you purchase shares of our common stock in this offering, you may not be able to resell those shares at or above the initial public offering price. An active or liquid market in our common stock may not develop upon completion of this offering or, if it does develop, it may not be sustainable.

Our stock price may be volatile or may decline regardless of our operating performance, resulting in substantial losses for investors purchasing shares in this offering.

The initial public offering price for the shares of our common stock sold in this offering will be determined by negotiation between the representatives of the underwriters and us. This price may not reflect the market price of our common stock following this offering. In addition, we expect the market price of our common stock may be volatile for the foreseeable future. The market price of our common stock may fluctuate significantly in response to numerous factors, many of which are beyond our control, including the factors listed below and other factors described in this “Risk Factors” section:

28

Table of Contents

In addition, stock markets have experienced extreme price and volume fluctuations that have affected and continue to affect the market prices of equity securities of many business services companies. Stock prices of many business services companies have fluctuated in a manner unrelated or disproportionate to the operating performance of those companies. In the past, stockholders have instituted securities class action litigation following periods of market volatility. If we were to become involved in securities litigation, it could subject us to substantial costs, divert resources and the attention of management from our business and adversely affect our business, results of operations and financial condition.

Substantial future sales of shares of our common stock could cause the market price of our common stock to decline.

Sales of a substantial number of shares of our common stock in the public market after this offering, or the perception that these sales might occur, could depress the market price of our common stock and impair our ability to raise capital through the sale of additional equity securities. We cannot predict the effect that such sales may have on the prevailing market price of our common stock.

All of our executive officers, senior management and directors and substantially all of the holders of our capital stock are subject to lock-up agreements that restrict their ability to transfer shares of our capital stock for 180 days from the date of this prospectus. Approximately              shares of our common stock will become eligible for sale upon expiration of the 180-day lock-up period. J.P. Morgan Securities LLC and Morgan Stanley & Co. LLC may, in their sole discretion, permit the parties to these lock-up agreements to sell shares prior to the expiration of the lock-up agreements.

In addition, as of September 30, 2013, there were 3,343,372 shares of common stock subject to outstanding options and 3,266 shares of common stock issuable upon settlement of restricted stock units. We intend to register all of the shares of common stock issuable upon exercise of these outstanding options and settlement of these outstanding restricted stock units, and upon exercise or settlement of any options or other equity incentives we may grant in the future, for public resale under the Securities Act of 1933, as amended. Accordingly, these shares will be able to be freely sold in the public market upon issuance as permitted by any applicable vesting requirements, subject to the lock-up agreements described above. These shares will become eligible for sale in the public market to the extent such options are exercised or such restricted stock units settle, subject to the lock-up agreements described above and compliance with applicable securities laws.

Holders of 19,032,854 shares of common stock issuable upon conversion of outstanding preferred stock as of September 30, 2013, and without giving effect to the sale of shares in this offering by the selling stockholders, have rights, subject to some conditions, to require us to file registration statements for the public resale of the common stock issuable upon conversion of such shares or to include such shares in registration statements that we may file for TriNet or our stockholders.

Purchasers in this offering will experience immediate and substantial dilution in the book value of their investment.

The initial public offering price of our common stock will be substantially higher than the pro forma net tangible book value per share of our common stock outstanding immediately following this offering. Therefore, if you purchase shares of our common stock in this offering at a price of $         , which is the midpoint of the

29

Table of Contents

estimated offering price range set forth on the cover page of this prospectus, you will experience immediate dilution of $          per share, the difference between the price per share you pay for our common stock and its pro forma net tangible book value per share as of September 30, 2013, after giving effect to the issuance of shares of our common stock in this offering. This dilution is due in large part to the fact that our earlier investors paid substantially less than the initial public offering price when they purchased their shares of our common stock. In addition, we have issued options and a warrant to acquire our common stock at prices significantly below the initial public offering price. To the extent that outstanding options and the warrant are ultimately exercised, there will be further dilution to investors purchasing our common stock in this offering. In addition, if the underwriters exercise their option to purchase additional shares from us or if we issue additional equity securities, you will experience additional dilution.

Future sales and issuances of our capital stock or rights to purchase our capital stock could result in additional dilution of the percentage ownership of our stockholders and could cause our stock price to decline.

We may issue additional securities after this offering. Future sales and issuances of our capital stock or rights to purchase our capital stock could result in substantial dilution to our existing stockholders. We may sell common stock, convertible securities and other equity securities in one or more transactions at prices and in a manner as we may determine from time to time. If we sell any such securities in subsequent transactions, investors may be materially diluted. New investors in these subsequent transactions could gain rights, preferences and privileges senior to those of holders of our common stock.

The existing ownership of capital stock by our executive officers, directors and their affiliates has the effect of concentrating voting control with our executive officers, directors and their affiliates for the foreseeable future, which will limit your ability to influence corporate matters.

Upon the closing of this offering, persons and entities affiliated with General Atlantic will beneficially own approximately     % of our outstanding common stock, and all of our directors, officers and their affiliates will beneficially own, in the aggregate, approximately     % of our outstanding common stock, in each case, assuming no exercise of the underwriters’ option to purchase additional shares. As a result, these stockholders will be able to determine substantially all matters requiring stockholder approval, including the election of directors and approval of significant corporate transactions, such as a merger or other sale of our company or its assets. This concentration of ownership could limit the ability of other stockholders to influence corporate matters and may have the effect of delaying or preventing a third party from acquiring control over us.

If securities or industry analysts do not publish research or reports about our business, or publish negative reports about our business, our share price and trading volume could decline.

The trading market for our common stock will depend in part on the research and reports that securities or industry analysts publish about us or our business, our market and our competitors. We do not have any control over these analysts. If one or more of the analysts who cover us downgrade our shares or change their opinion of our shares, our share price would likely decline. If one or more of these analysts cease coverage of our company or fail to regularly publish reports on us, we could lose visibility in the financial markets, which could cause our share price or trading volume to decline.

We may invest or spend the proceeds of this offering in ways with which you may not agree or in ways which may not yield a return.

We expect to use the net proceeds that we receive from this offering for repayment of indebtedness, general corporate purposes, including working capital, sales and marketing activities, general and administrative matters and capital expenditures. We may also use a portion of the net proceeds to acquire complementary businesses, products, services or technologies. Our management will have considerable discretion in the application of the net proceeds, and you will not have the opportunity, as part of your investment decision, to assess whether the proceeds are being used appropriately. The net proceeds may be used for corporate purposes that do not increase the value of our business, which could cause the price of our stock to decline.

30

Table of Contents

Anti-takeover provisions in our charter documents and under Delaware law could make an acquisition of our company more difficult, limit attempts by our stockholders to replace or remove our current management and limit the market price of our common stock.

Provisions in our certificate of incorporation and bylaws, as they will be amended and restated in connection with this offering, may have the effect of delaying or preventing a change of control or changes in our management. Our amended and restated certificate of incorporation and bylaws will include provisions that:

These provisions may frustrate or prevent any attempts by our stockholders to replace or remove our current management by making it more difficult for our stockholders to replace members of our board of directors, which is responsible for appointing the members of our management. In addition, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the Delaware General Corporation Law, which generally prohibits a Delaware corporation from engaging in any of a broad range of business combinations with any holder of at least 15% of our capital stock for a period of three years following the date on which the stockholder became a 15% stockholder.

In making your investment decision, you should not rely on information in public media that is published by third parties. You should rely only on statements made in this prospectus in determining whether to purchase our common stock.

You should carefully evaluate all of the information in this prospectus. We have in the past received, and may continue to receive, media coverage, including coverage that is not directly attributable to statements made by our directors, officers and other employees. We cannot confirm the accuracy of such coverage. You should rely only on the information contained in this prospectus in determining whether to purchase our shares of common stock.

31

Table of Contents