PEO Payroll Taxes: Who Files, Who Pays, Who Is Liable

Inside a PEO arrangement, another company calculates, deposits, and reports federal employment taxes. The contract and federal tax rules determine whether the client, the PEO, or both remain liable when a filing or deposit is wrong.

Under federal tax law, employment tax responsibility follows from being the employer or from a specific statutory arrangement rather than a label such as co-employment. The IRS explains that using a PEO does not by itself relieve the client of employment tax liability, and that the analysis turns on the facts of the arrangement. Certified PEOs receive specific statutory treatment.

The common-law employer baseline

Federal employment taxes (income tax withholding, Social Security and Medicare under FICA, and federal unemployment under FUTA) attach to the employer. For most PEO clients, the client remains the common-law employer of its workforce: it hires, directs, evaluates, and fires. The Internal Revenue Code does not recognize "co-employer" as a tax status. So the starting position, before any special arrangement, is that the taxes are yours.

Three federal tax arrangements

Payroll service provider or reporting agent. The provider files under your EIN, and you remain fully liable. The IRS cautions employers that they stay responsible for deposits even when a provider fails. An employer can therefore owe taxes again after funding a provider that did not remit them.

Section 3504 agent. The employer appoints an agent (via Form 2678) that withholds, reports, and pays employment taxes. The IRS describes the arrangement as creating shared liability: both the agent and the employer remain on the hook. Many non-certified PEO structures work this way or similarly. The practical consequence: if the PEO collects your taxes and does not remit them, the IRS can still collect from you.

Certified PEO. A CPEO that has a qualifying contract in effect is, as the IRS puts it, generally solely liable for federal employment taxes on remuneration it pays to worksite employees. Certification is entity-specific and voluntary, requires bonding and audited financials, and can be verified on the IRS public listings. Different treatment can apply to individuals who are not worksite employees under the rules, and the protection is only as good as the match between the certified entity and the entity on your contract.

The forms, and what each one tells you

• Form 941 reports quarterly wages and employment taxes. A PEO filing in aggregate attaches Schedule R, which allocates the aggregate numbers to each client's EIN. Your allocation is your audit trail: request it quarterly and reconcile it against your invoices.
• Form 940 reports annual FUTA. Aggregate filers allocate it with Schedule R (Form 940) as well.
• Form 8973 is the CPEO-customer reporting agreement: the CPEO files it when your contract starts and when it ends. The end-date filing marks where CPEO liability stops and yours resumes, which makes it a transition document worth confirming, not assuming.

Wage bases and the mid-year problem

Social Security and FUTA taxes apply up to annual wage bases. When the entity treated as the employer changes mid-year without successor treatment, wage bases can restart, and the company and its employees can overpay for the year. Federal regulations give qualifying CPEO contracts predecessor-and-successor treatment for these wage bases at start and end, which is one of certification's most concrete benefits for anyone transitioning mid-year. With a non-certified arrangement, require an employee-level analysis of wage-base treatment before choosing an effective date, and price January 1 against the alternative. The PEO wage-base restart guide provides a worked example and the fields to model for every employee.

State unemployment requires a separate analysis in every state. Reporting method, account ownership, rate, and post-exit experience treatment vary by state and sometimes by election within a state. Federal rules do not decide those questions.

What to verify before and during the relationship

1. Match the entity. The legal entity on your service agreement must be the one with the tax status you are relying on. Check CPEO status against the IRS listing and record the EIN and effective date.
2. Get the allocation. Ask for your Schedule R allocation each quarter, or the equivalent client-level filing confirmation, and reconcile it against the taxes your invoice says were collected.
3. Confirm the 8973s. At the start and end of a CPEO relationship, confirm the Form 8973 filings and keep copies.
4. Verify tax deposits. For non-certified arrangements, use IRS transcripts or e-Services when available to confirm that deposits reached the correct account. Address verification rights in the service agreement.
5. Plan transitions on paper. Entry and exit are where liability, wage bases, and filing responsibility change hands. Both events deserve a written tax-transition memo naming which entity files which forms for which periods of the year.

How to weigh tax protection

If a failed remittance would seriously damage your company, give CPEO status substantial weight or require documented financial assurance and verification rights from a non-certified PEO. In either arrangement, match the legal entity, filing authority, and tax records to the service agreement.