California does not license Professional Employer Organizations under a single statute, so PEO regulations in California come from a patchwork of agencies covering payroll taxes, workers’ compensation, workplace safety, and labor law. The practical consequence for a client business is that entering a co-employment relationship shifts administrative work to the PEO but leaves the client jointly responsible for most of what can go wrong. Both sides are employers in the eyes of California enforcement agencies, and the written contract does not override that.
Co-Employment and Why Both Sides Are Liable
In a PEO arrangement, the PEO and the client are treated as employers of the same workers at the same time. The PEO acts as the administrative employer handling payroll, tax filings, and benefits. The client remains the worksite employer, directing daily work and making hiring, discipline, and termination decisions. Neither party is a supporting player; both carry real legal obligations.
Cal/OSHA’s dual-employer inspection policy illustrates how this works in practice. A PEO that exercises direction and control over workers through hiring, firing, reassigning, disciplining, or setting wages is treated as the “primary employer” subject to Cal/OSHA jurisdiction, regardless of what the written contract says. The client is classified as the “secondary employer,” and both can be cited for safety violations found at the worksite.1California Department of Industrial Relations. Division of Occupational Safety and Health Policy and Procedures Manual P&PC-1D – Dual-Employer Inspections The actual working relationship controls; contract language does not.
Which Agencies Regulate PEOs in California
California has no dedicated PEO licensing statute, unlike roughly 40 other states. PEOs must instead satisfy requirements imposed by several agencies independently. The Employment Development Department oversees payroll tax reporting. The Department of Industrial Relations enforces labor law and workplace safety. The Department of Insurance regulates the workers’ compensation coverage a PEO arranges for its clients. A PEO out of compliance with any one of these agencies can leave its client exposed.
Assembly Bill 1515, introduced in the 2025–2026 session, would require PEOs to register with the state and pay a registration fee before offering services in California. As of early 2026, that bill has not been enacted. Until it is, there is no state registry to consult, and the vetting burden sits with the client.
Workers’ Compensation Obligations
Every California employer must secure workers’ compensation coverage through an authorized insurer or by holding a certificate of self-insurance from the Director of Industrial Relations.2California Legislative Information. California Code LAB 3700 – Securing Payment of Compensation When a PEO administers coverage, it typically does so under a master policy. Verify that the policy is active, that the carrier is authorized in California, and that your workforce is explicitly named.
Operating without valid coverage is a criminal offense. A first conviction is a misdemeanor carrying up to one year in county jail, a fine of up to double the premium that should have been paid (with a minimum of $10,000), or both. A second or subsequent conviction raises the fine to up to triple the unpaid premium, with a minimum of $50,000.3California Legislative Information. California Code LAB 3700.5 – Failure to Secure Payment of Compensation If the PEO fails to maintain coverage, the client can be pursued as a co-employer.
Extra Rules for Construction Contractors
Construction businesses face additional scrutiny from the Contractors State License Board. All construction employers must carry workers’ compensation coverage even with only one employee. Certain classifications, including C-8 (Concrete), C-20 (HVAC), C-22 (Asbestos Abatement), C-39 (Roofing), and C-61/D-49 (Tree Service), must carry coverage or a valid self-insurance certificate whether or not they have any employees, and cannot file an exemption.4Contractors State License Board. Workers’ Compensation Requirements
When a contractor uses a PEO for coverage, the CSLB requires supplemental paperwork. Licensees with the specialty classifications above, or those who qualify their license through a Responsible Managing Employee, must submit addendum forms with their certificate of insurance documenting the PEO relationship and confirming coverage extends to dispatched employees.5Contractors State License Board. CSLB Certificate of Insurance Requirements
What the Client Stays Liable For
The co-employment structure means both parties can be pursued for the major categories of California employment claims: wage and hour disputes, discrimination and harassment under the Fair Employment and Housing Act, and workplace safety violations. A PEO contract will normally allocate indemnification, but indemnification is a private matter between the two companies. It does not stop a government agency or an employee from choosing which party to pursue.
Labor Code 2810.3 Joint Liability
California Labor Code Section 2810.3 makes client employers jointly and civilly liable with labor contractors for wage payments and workers’ compensation coverage failures.6California Legislative Information. California Code LAB 2810.3 – Client Employer Liability PEOs may qualify for an exemption if the arrangement meets California’s definition of an employee leasing arrangement and the contract explicitly requires the client to assume all civil legal responsibility. The exemption is not automatic. If your PEO contract lacks that assumption-of-liability language, the default shared-liability rule applies.
Workplace Safety Stays with the Worksite
The client remains responsible for maintaining safe conditions and implementing a written Injury and Illness Prevention Program, which California requires of every employer.7Department of Industrial Relations. Cal/OSHA Overview of Employer Responsibilities Inspections, hazard corrections, and safety training belong to the worksite employer. Pointing to the PEO contract does not shift that duty.
I-9 Verification
A PEO may complete Form I-9 as an authorized representative, but the employer remains legally liable for any verification violations, including mistakes made by the representative.8U.S. Citizenship and Immigration Services. Instructions for Form I-9, Employment Eligibility Verification If your PEO handles I-9 processing, you are still on the line for incomplete, late, or missing forms. Periodic audits of your I-9 files are worth the trouble.
Federal CPEO Certification Changes the Tax Picture
At the federal level, the IRS runs a voluntary certification program for PEOs under Section 7705 of the Internal Revenue Code. A Certified Professional Employer Organization must meet ongoing requirements including independent financial audits, accrual-method accounting, and a surety bond equal to the greater of 5 percent of its prior-year federal employment tax liability (capped at $1,000,000) or $50,000.9GovInfo. 26 USC 7705 – Certified Professional Employer Organizations
Under Section 3511, a CPEO is treated as the sole employer for federal employment tax purposes with respect to wages it remits to worksite employees. The client is not jointly liable for those federal payroll taxes, a protection that does not exist with a non-certified PEO.10Office of the Law Revision Counsel. 26 USC 3511 – Certified Professional Employer Organizations If a non-certified PEO collects payroll taxes from a client and fails to remit them to the IRS, the client can be held responsible. With a CPEO, that risk shifts to the PEO.
When a CPEO begins or ends a service contract with a client, it must file IRS Form 8973 within 30 days. A newly certified CPEO has six months to file Form 8973 for existing client relationships.11Internal Revenue Service. Instructions for Form 8973 – Certified Professional Employer Organizations Note that CPEO status is a federal protection. It does not exempt the PEO or the client from California’s state-level obligations, including workers’ compensation and Cal/OSHA duties. If a PEO claims certification, ask for its CPEO number and confirm it against the IRS public listing.12Internal Revenue Service. CPEO Public Listings
How to Vet a PEO Before Signing
Because California has no PEO registry, due diligence falls on the client. A few things are worth confirming before you sign.
- Verify CPEO certification against the IRS public listing. It is the strongest single indicator of financial and operational stability, and it protects you from joint federal tax liability.
- Confirm workers’ compensation coverage with a certificate of insurance naming your company, issued by a California-authorized carrier. For construction businesses, confirm the PEO can provide the CSLB-required addendum forms.
- Read the co-employment agreement for indemnification language, allocation of liability for wage claims and safety violations, and whether the contract satisfies the Labor Code 2810.3 exemption requirements. Vague or one-sided indemnification is a red flag.
- Ask for recent financial audits and proof of bonding. A CPEO must maintain audited financials and a surety bond, and even non-certified PEOs should be willing to share this.
- Understand the exit process. How quickly do payroll tax accounts transfer back? Who retains employee records? What happens to benefits coverage during transition? A messy separation can leave employees without insurance and create reporting gaps with the EDD.
PEOs charge either a flat per-employee fee or a percentage of total payroll. Get the fee structure in writing before committing, and compare it against the cost of handling payroll, benefits, and compliance in-house.