The history of PEOs: origins, evolution, and growth explained

The professional employer organization (PEO) industry traces its roots to employee leasing arrangements that began in the late 1960s, gained momentum in the 1970s, evolved through federal tax legislation in the 1980s, professionalized through state regulation in the 1990s, and gained formal IRS certification through the CPEO program in 2016-2017. Today, approximately 500 PEOs operate in the United States. NAPEO’s 187 member PEOs serve over 230,000 businesses and 4.5 million worksite employees, generating more than $372 billion in revenue according to NAPEO’s October 2025 press release.

The impact goes beyond scale. According to NAPEO’s 2024 white paper, businesses that use PEOs have growth rates more than twice as high as comparable non-PEO businesses (4.3% annually vs 1.9%), experience employee turnover rates that are 12 percent lower, and are 50 percent less likely to go out of business. NAPEO also reports that PEOs deliver approximately a 27 percent return on investment in cost savings alone. PEO awareness among business owners rose 48 percent between 2018 and 2022, reaching approximately 65% (NAPEO/PRNewswire 2023), reflecting the industry’s growing visibility and the increasing regulatory burden that drives small businesses to seek outside HR support.

This guide traces how PEOs moved from an informal tax workaround to a regulated, IRS-certified industry that handles payroll, benefits, compliance, and risk management for small and mid-sized businesses across all 50 states.

The PEO industry’s development can be tracked through a series of legislative, regulatory, and organizational milestones spanning five decades.

The PEO model originated in the late 1960s when three businessmen, Eugene Boffa Sr., Louis Calmare Sr., and Joseph Martinez Sr., launched employee leasing arrangements. The concept was then popularized in the early 1970s by consultant Marvin R. Selter, who leased the staff of a doctor’s office in Southern California. The arrangement was simple. An employer would terminate its employees, who would then be rehired by the leasing company. The leasing company would lease them back to the original employer, handling payroll, benefits, and tax filings while the employer kept day-to-day operational control. Selter’s work brought the concept into wider commercial practice and established the basic operational template that the industry would build on for decades.

Small businesses benefited most from these early arrangements. Government compliance, payroll administration, and workers’ compensation solutions were the primary services these predecessor companies offered. For a small business owner without an HR department, handing off payroll processing, tax filings, and insurance administration to a specialized company was a practical solution to a real operational problem. The core value proposition that drives the modern PEO industry, allowing small businesses to outsource employment complexity so they can focus on running their business, was already present in these earliest arrangements.

The model gained significant traction because of a gap in the Internal Revenue Code’s retirement plan rules. The Employee Retirement Income Security Act (ERISA) of 1974 established nondiscrimination provisions under IRC Sections 401(a)(4) and 410(b) that required employers to offer retirement benefits equitably across highly compensated and rank-and-file employees. However, there were no leased-employee aggregation rules requiring organizations without common ownership to treat leased workers as their own employees for nondiscrimination testing purposes. This gap meant that employee leasing allowed business owners to keep highly compensated employees in one entity and lease lower-paid staff through a separate company, effectively circumventing the nondiscrimination requirements for qualified retirement plans.

The loophole was not the only driver of growth, but it was the most powerful one. It allowed business owners and professionals (doctors, lawyers, executives) to set up generous retirement plans for themselves and a small group of highly compensated employees, while the rest of their workforce was technically employed by the leasing company and excluded from those plans. The tax advantages were substantial, and the arrangement was entirely legal under the existing rules. This gap between the intent of the nondiscrimination rules and the reality of the leasing structure is what eventually drew Congressional attention.

Congress responded in 1982 with the Tax Equity and Fiscal Responsibility Act (TEFRA), which added Section 414(n) to the IRC specifically to close the leased-employee aggregation gap. Section 414(n) generally required that leased employees be treated as employees of the recipient employer for retirement plan purposes, closing the loophole that had made the arrangement so attractive for tax avoidance. However, TEFRA also included a safe harbor under Section 414(n)(5) that allowed compliant leasing arrangements to continue if the leasing organization maintained a qualifying pension plan with at least 7.5% employer contributions. The Tax Reform Act of 1986 later raised this safe harbor threshold to 10%.

The safe harbor provision was significant because it gave the legitimate portion of the industry a path forward. While the pure tax-avoidance motive was curtailed, businesses that genuinely benefited from outsourcing payroll, benefits administration, and HR compliance could still use leasing arrangements as long as the leasing company maintained a qualifying retirement plan for leased employees. The 1986 increase to 10% made compliance more expensive but didn’t eliminate the model. Instead, it pushed the industry to justify its existence on operational value rather than tax arbitrage, a shift that would ultimately define the modern PEO.

The rapid growth of employee leasing between the mid-1970s and early 1980s attracted operators who saw the model as a way to collect large payroll funds without fulfilling their obligations. Some leasing companies failed to remit payroll taxes to the IRS. Others offered self-funded workers’ compensation plans that were poorly managed or outright fraudulent, leaving injured workers without coverage. Health insurance premiums were collected but claims went unpaid. The combination of handling large payroll volumes and operating in a regulatory vacuum created an environment where bad actors could collect substantial sums, divert them, and disappear before the consequences caught up.

The scale of the problem was not trivial. Because leasing companies functioned as the employer of record for tax and insurance purposes, a single fraudulent operator could leave dozens or hundreds of client businesses exposed to unpaid tax liabilities, uncovered workers’ compensation claims, and lapsed health insurance. Workers who believed they had coverage discovered they didn’t when they filed claims. Client businesses that believed their payroll taxes were being remitted found themselves liable for the unpaid amounts plus penalties. The IRS, state tax agencies, and insurance regulators all had reason to scrutinize the industry.

These failures created a credibility crisis for the entire industry. The fraud and incompetence of a few operators gave employee leasing what early industry leaders described as "a really black eye." Legitimate operators who were running compliant operations, maintaining proper reserves, and fulfilling their obligations to workers and tax agencies found themselves fighting the same reputational damage as the fraudulent ones. Without a regulatory framework to separate the responsible operators from the bad actors, the entire concept of employee leasing risked being discredited. It was this pressure, combined with TEFRA’s tightening of the tax benefits, that pushed responsible industry participants to organize and advocate for regulation that would establish minimum standards and weed out unqualified operators.

In response, industry leaders formed the National Staff Leasing Association (NSLA) in November 1984. Fourteen staff leasing companies met and decided to create the association, electing Andy Butler of Office Staff Services in Virginia to serve as the first NSLA president. The NSLA was the first trade association for the employee leasing industry, and its formation marked the beginning of the industry’s transition from an unregulated collection of individual operators to an organized profession with shared standards and a collective voice. The founding members recognized that self-regulation and advocacy for state-level oversight were essential for the industry’s long-term survival.

In 1991, two critical developments happened simultaneously. The National Association of Insurance Commissioners (NAIC) adopted both an Employee Leasing Model Regulation and an Employee Leasing Registration Model Act. Together, these standardized workers’ compensation data collection, policy forms, experience rating plans, and registration requirements for companies using employee leasing arrangements. This was a limited-purpose framework focused on workers’ compensation insurance, not a broad co-employment regulation. That same year, Arkansas passed the nation’s first PEO licensing bill in June 1991. Florida followed months later with its Employee Leasing Licensing Law, establishing the co-employment framework that would become the foundation of the modern PEO model and providing the template that other states would follow over the next two decades.

The shift from "employee leasing" to "professional employer organization" happened in the mid-1990s as the industry worked to distance itself from the negative connotations of leasing and establish a more professional identity. Through the late 1980s and early 1990s, the industry advocated for state-level recognition of co-employment relationships, and states including Florida, Arkansas, and Texas established statutory frameworks that defined the legal relationship between the PEO, the client company, and the worksite employees. These state statutes established PEOs’ right to withhold and remit federal income tax withholding, FICA (Social Security and Medicare), and FUTA on behalf of worksite employees as part of the co-employment arrangement. Co-employment is a state-law concept. The IRS does not use "co-employer" as a federal tax category.

In 1994, the NSLA formally rebranded as the National Association of Professional Employer Organizations (NAPEO). The name change was championed by industry leaders including Carlos Saladrigas, then a former NAPEO president and co-founder of Vincam (1984, Miami), who came from the HMO industry and wanted to distinguish the industry from the disposable connotation of "leasing" and position it more like the HMO model in healthcare, where a specialized organization manages a complex function on behalf of a client. The new PEO model centered on co-employment, a legal framework recognized by state statutes under which the PEO and the client company share certain employer responsibilities. The PEO typically handles payroll, tax administration, PEO benefits, and compliance, while the client retains control over hiring, firing, and day-to-day management of its workforce.

The co-employment model offered more services than employee leasing companies had provided and created a shared-risk platform that helped insulate client companies from the complexities of employment regulation. Unlike the old leasing model where employees were technically terminated and rehired, co-employment maintained the existing employment relationship while adding the PEO as a co-employer for specific administrative and compliance functions. This distinction was legally and practically important because it preserved the client’s ability to manage its workforce directly while gaining the PEO’s scale, expertise, and infrastructure.

Through the late 1990s and 2000s, PEOs expanded their service scope from basic payroll and workers’ compensation to full-scope HR management, including benefits administration, regulatory compliance, employee handbooks, OSHA compliance, talent management, and assistance navigating increasingly complex employment laws. NAPEO developed a PEO Model Act that provided a template for state-level oversight, and states steadily adopted PEO-specific licensing and registration requirements. As states adopted these frameworks through the 1990s and 2000s, co-employment became the industry’s defining legal structure and the regulatory guardrails that had been missing during the leasing era were firmly established.

The Certified Professional Employer Organization (CPEO) program was the most significant federal legislative recognition of PEOs in the industry’s history. It was established by the Small Business Efficiency Act (SBEA), which was enacted as part of the Tax Increase Prevention Act (TIPA) of 2014, Public Law 113-295. NAPEO’s advocacy was instrumental in getting the legislation passed. The IRS began accepting CPEO applications on July 1, 2016, with the first certifications taking effect in 2017. The IRS maintains a public list of certified PEOs that is updated quarterly (verify the current count at irs.gov/cpeo).

The CPEO certification created a formal IRS designation for PEOs that meet strict financial, tax, and operational requirements. The key benefit for businesses using a CPEO is the elimination of the "double tax" problem. Before CPEOs, when a client switched PEOs or left a PEO mid-year, the federal wage base for Social Security and FUTA taxes would reset, causing the employer to pay these taxes twice on the same wages. Under IRC Section 3511, CPEOs can assume federal employment tax liability for worksite employees, and wage base credits transfer without interruption when employees move between CPEOs or back to the client company. This protection applies only to CPEOs. For non-CPEO PEOs, the client generally remains the common-law employer and retains liability if the PEO fails to remit taxes.

CPEO status requires annual audited financial statements, bond or security deposits, tax compliance verification, and background checks on controlling persons. The certification requirements are deliberately stringent because the CPEO is assuming federal tax liability that would otherwise rest with the client company. For small businesses evaluating PEO providers, the CPEO designation provides a meaningful signal of financial stability, operational competence, and tax compliance commitment. The IRS maintains a public list of certified PEOs so businesses can verify a provider’s certification status before entering a co-employment relationship.

The Affordable Care Act (ACA), enacted in 2010, became one of the most significant drivers of PEO adoption for small businesses. The ACA introduced complex employer health insurance mandates, including the employer shared responsibility provisions (the "employer mandate") for applicable large employers, reporting requirements under IRC Sections 6055 and 6056, and the administrative burden of tracking employee hours, determining full-time equivalency, and managing the intersection of benefits administration with tax reporting. For small businesses approaching or crossing the 50-employee threshold, ACA compliance became a substantial operational challenge that PEOs were uniquely positioned to handle.

Beyond the ACA, employment regulations at both the federal and state levels have grown increasingly complex. Changes in labor laws, tax regulations, workplace safety requirements, and state-specific employment mandates create a compliance web that small businesses struggle to manage without dedicated HR and legal expertise. PEOs stay on top of this shifting regulatory environment and keep their clients positioned to comply with current requirements. For a 25-person company without an HR department, the difference between staying compliant and facing regulatory penalties often comes down to whether they have a PEO handling compliance monitoring, reporting, and policy updates on their behalf.

The COVID-19 pandemic in 2020 became the most significant stress test in PEO industry history, and PEOs emerged as critical partners for small businesses facing unprecedented regulatory and operational uncertainty. Suddenly, every small business was thrust into uncharted territory. Regulations, rules, and workplace safety guidelines were changing daily, and business owners who had never dealt with furloughs, remote work policies, or federal disaster relief programs found themselves needing expert guidance immediately.

When the Paycheck Protection Program (PPP) launched, small businesses needed to apply quickly with accurate payroll data to secure forgivable loans. PEOs provided the payroll records, tax documentation, and application support that many small employers couldn’t generate on their own within the compressed timelines. 

PEOs also helped clients claim Employee Retention Tax Credits (ERTC), work through constantly changing workplace safety requirements, manage furloughs and layoffs in compliance with federal and state WARN Act requirements, restructure operations for remote work, and make critical employment decisions about workforce reductions. The pandemic demonstrated that PEOs’ value extends beyond routine payroll and benefits administration. In a crisis where the rules changed daily and the consequences of non-compliance were severe, PEOs provided the strategic HR guidance and regulatory expertise that small businesses needed to survive.

The PEO industry has grown steadily over the past two decades. Approximately 500 PEOs operate in the United States. NAPEO’s October 2025 press release reports that its 187 member PEOs serve over 230,000 businesses and co-employ more than 4.5 million worksite employees, generating more than $372 billion in revenue. Total industry revenue is estimated at approximately $414 billion. PEO penetration reaches approximately 15% among employers with 10 to 499 employees, according to NAPEO’s data. PEO recognition now exists in law in 48 states, and NAPEO’s State Government Affairs Committee maintains a dedicated state action plan enacted yearly to broaden influence and advocacy in the remaining jurisdictions.

NAPEO’s 2024 white paper shows measurable business outcomes for PEO clients. Businesses using PEOs have growth rates more than twice as high as comparable non-PEO businesses (4.3% annually versus 1.9%). Employee turnover is 12 percent lower among PEO clients. PEO-using businesses are 50 percent less likely to go out of business permanently. And PEOs deliver approximately a 27 percent return on investment in cost savings alone. These aren’t hypothetical projections; they come from NAPEO-commissioned research comparing PEO-using businesses against matched control groups of similar size and industry.

The industry’s influence with federal and state governments has grown substantially. NAPEO has established its own political action committee (PAC) to support federal advocacy priorities by strengthening relationships with influential policymakers. NAPEO and its members regularly testify on behalf of the industry in state capitals and before Congressional committees.

The global PEO market was valued at approximately $66 billion in 2024 according to estimates from Straits Research, with projections reaching $170 billion by 2033 at a CAGR of 11.10%. While PEOs remain a predominantly US model, demand is growing internationally as companies look for compliant ways to hire across borders without establishing local entities. The rise of remote work, the gig economy, and AI-driven HR technology are reshaping the workforce, and PEOs are already adapting by offering flexible HR solutions tailored to a more dynamic and geographically dispersed workforce.

Technology has fundamentally reshaped how PEOs deliver services, moving the industry from paper-based payroll processing to cloud-based platforms that provide real-time access to HR, payroll, benefits, and compliance data. The advent of cloud computing and modern HRIS (Human Resource Information System) platforms means that employers and employees can now access payroll information, benefits enrollment, time and attendance tracking, and HR resources from anywhere with an internet connection. This technological shift has increased operational efficiency, improved the accuracy of data management and compliance reporting, and enabled PEOs to serve geographically distributed workforces that would have been impossible to manage with earlier systems.

For small businesses, PEO technology platforms often represent a significant upgrade from whatever ad hoc systems they were using before. A 15-person company that was processing payroll through spreadsheets and tracking PTO in an email thread gains access to enterprise-grade HRIS, automated payroll processing, digital benefits enrollment, compliance dashboards, and employee self-service portals through its PEO relationship. The PEO’s technology investment is spread across hundreds of clients and thousands of worksite employees, giving each individual client access to systems they couldn’t justify building or licensing on their own. Forward-thinking PEOs are also incorporating data analytics and AI-driven insights to help clients identify workforce trends, predict turnover, and make strategic hiring decisions.

PEOs handle payroll by becoming the employer of record for tax purposes, processing wages, withholding federal and state taxes, remitting payroll taxes to the IRS and state agencies, and generating W-2s for all worksite employees. PEOs for small businesses are especially valuable because they bring dedicated payroll expertise, automated systems, and compliance teams that a 20-person company couldn’t afford to hire in-house.

The employer of record arrangement means the PEO’s federal EIN appears on payroll tax filings and W-2s for worksite employees. The PEO processes payroll on its own systems, calculates withholdings, files quarterly and annual tax returns, handles year-end reporting, and manages garnishments and deductions. For the small business owner, this eliminates the need to track changing federal and state tax rates, meet filing deadlines, calculate overtime and deductions, and manage the administrative burden that comes with being a payroll processor. The PEO handles the mechanics; the client company retains control over who gets hired, what they’re paid, and how the work gets done.

A missed payroll tax deposit or a late W-2 filing triggers IRS penalties that can be costly for a small company. CPEOs specifically can assume federal employment tax liability under IRC Section 3511, which means the CPEO, not the client, is responsible if taxes aren’t remitted correctly. For non-CPEO PEOs, the client retains this liability. This distinction is one of the key benefits that businesses should evaluate when choosing a provider, because the difference between a CPEO and a non-CPEO determines who is ultimately on the hook if something goes wrong with tax remittances.

PEOs also handle workers’ compensation administration, unemployment insurance management, garnishment processing, new-hire reporting, ACA compliance and reporting, OSHA compliance, employee handbooks, and HR policy development. The PEO’s scale (thousands of worksite employees across hundreds of clients) gives it purchasing power for benefits and insurance that individual small businesses can’t match. PEOs provide access to high-quality, cost-effective health insurance plans with efficiencies typically unavailable to small and mid-size employers, enabling client organizations to offer health care plans that attract and retain workers. For companies looking to expand beyond the US, an international PEO can extend similar services across borders, handling local compliance in countries where the company doesn’t have its own entity.

The concept behind PEOs started in the late 1960s when Eugene Boffa Sr., Louis Calmare Sr., and Joseph Martinez Sr. launched employee leasing arrangements. Consultant Marvin R. Selter popularized the model in the early 1970s in Southern California. The modern PEO model, based on co-employment rather than leasing, took shape in the early 1990s when Arkansas passed the first state PEO licensing bill in June 1991, Florida established the co-employment framework months later, and the industry rebranded through NAPEO in 1994. The CPEO certification program, which added formal IRS oversight and certification, became operational in 2017.

Employee leasing involves terminating employees and rehiring them through a staffing company, which then leases them back to the original employer. In a PEO arrangement, the client company’s employees aren’t terminated or transferred. Instead, the PEO enters into a co-employment relationship where it handles HR administration, payroll, and compliance while the client company retains operational control and the ability to hire and terminate employees directly. The co-employment model offers more services than leasing and creates a shared-risk platform for employment regulation, whereas employee leasing was primarily a mechanism for outsourcing payroll and, in its early days, exploiting retirement plan nondiscrimination loopholes.

CPEO stands for Certified Professional Employer Organization, a designation established by the Small Business Efficiency Act (SBEA) of 2014 (part of the Tax Increase Prevention Act, Public Law 113-295) and administered by the IRS. CPEOs meet strict financial, tax, and operational requirements. The key advantage is that a CPEO can assume federal employment tax liability for worksite employees under IRC Section 3511, preserving wage base credits when employees move between PEOs and eliminating the double-tax problem that existed before certification. The IRS maintains a public list of certified PEOs, updated quarterly at irs.gov/cpeo.

Approximately 500 PEOs currently operate in the United States. NAPEO’s 187 member PEOs serve over 230,000 businesses and co-employ more than 4.5 million worksite employees, generating more than $372 billion in revenue, according to NAPEO’s October 2025 press release. Total industry revenue is estimated at approximately $414 billion. PEO recognition exists in law in 48 states. Per NAPEO’s 2024 white paper, businesses using PEOs have growth rates more than twice as high as non-PEO businesses, experience 12 percent lower employee turnover, and are 50 percent less likely to go out of business.

The primary difference is the co-employment relationship. A PEO becomes a co-employer under state law and takes on shared legal responsibility for employment tax filings, workers’ compensation, and compliance. HR outsourcing firms provide administrative services but don’t enter a co-employment arrangement and don’t become the employer of record for tax purposes. The co-employment model gives PEOs purchasing power for benefits and insurance that HR outsourcing firms can’t match, because the PEO aggregates thousands of worksite employees across hundreds of clients into a single benefits pool. This is why PEOs can offer small businesses access to health insurance, retirement plans, and workers’ compensation coverage at rates typically reserved for much larger employers.

Yes. PEOs are regulated at both the state and federal levels. At the state level, 48 states have some form of PEO recognition in law, and many require specific licensing or registration. NAPEO developed a PEO Model Act that has served as the template for state-level regulatory frameworks. At the federal level, the CPEO certification program under IRC Sections 3511 and 7705 provides IRS oversight of certified PEOs, including requirements for annual audited financial statements, bond or security deposits, tax compliance verification, and background checks on controlling persons. The regulatory framework surrounding the modern PEO industry provides guardrails that did not exist during the employee leasing era, which is a direct result of the industry’s own advocacy for proper oversight through NAPEO.