If you are working out how to choose a payroll provider for the businesses your firm serves, start with the IRS arrangement the provider will operate under, because that decides who is liable when a deposit is missed. With an ordinary payroll service or reporting agent, the client employer stays fully liable for its employment taxes. Only a certified professional employer organization (CPEO), and a few agent arrangements, shift or share that liability.
Once the arrangement is clear, the rest of the decision is practical: deposits made through EFTPS under the client's own EIN, platform and state coverage, year-end forms, error terms and a clean exit. This guide explains how to choose a payroll provider for accounting firm clients using those checks, and it includes a worked example of verifying a provider's deposits each quarter.
This page assumes the decision to outsource has already been made. If a client is still weighing it, our article on the reasons to outsource payroll covers that question. This guide does not rank or recommend any named vendor.
The IRS groups outside payroll firms under the heading "third-party payers." Publication 15 states the default rule plainly: "An employer who outsources payroll and related tax duties ... to a third-party payer will generally remain responsible for those duties, including liability for the taxes." It adds: "You remain responsible if the third party fails to perform any required action."
The IRS third party arrangement chart lays out the main types side by side. The table below summarizes it.
| Arrangement | IRS form | EIN used on returns | Who is liable for the client's employment taxes |
|---|---|---|---|
| Payroll service provider (PSP) | None required | Client's EIN | Client employer only |
| Reporting agent (a type of PSP) | Form 8655 | Client's EIN | Client employer only |
| Agent approved under section 3504 | Form 2678 | Agent's EIN | Client and agent jointly |
| Certified PEO (CPEO) | Form 8973 | CPEO's EIN | Generally the CPEO alone for worksite employees |
For the first two rows, the IRS chart says: "Employer/Client, not the PSP, remains liable for ensuring all tax returns are filed timely." For a CPEO, the same chart says "Generally, the CPEO is solely liable" for wages it pays to worksite employees, while noting that the "CPEO and customer may both be liable with regard to remuneration the CPEO pays to non-worksite employees."
IRS certification is voluntary, so a provider can call itself a PEO without being a CPEO. The liability shift applies only to certified organizations. Our comparison of PEO vs in-house payroll explains the co-employment model if a client is considering one.
The checks below apply whether the provider is a software platform with tax filing built in, a full-service bureau, or an outsourced processing team working inside the client's existing system.
Ask the provider which arrangement it will use and get the answer in the service agreement. If the provider will sign and file returns and make deposits electronically, it should be acting as a reporting agent. The IRS page about Form 8655 says the form is used "to authorize a reporting agent to" "Sign and file certain returns" and "Make deposits and payments for certain returns." Keep a copy of the signed Form 8655 in the client file and note which tax forms and periods it covers.
If a provider claims to be a CPEO, check the IRS CPEO public listings. The IRS says the list "will be updated to reflect newly certified CPEOs by the 15th day of the first month of every calendar quarter." The same page warns that if certification is revoked, "the customers may also be liable (as of the effective date of revocation) for federal employment taxes." Recheck the list at least once a quarter for any client using a CPEO.
Publication 15 says an employer using a PSP "should ensure the PSP is using EFTPS to make federal tax deposits on behalf of the employer so the employer can confirm that the payments are being made on its behalf." For reporting agents the rule is firmer: "A reporting agent must use EFTPS to make federal tax deposits on behalf of an employer."
EFTPS costs the client nothing. Publication 15 notes that "EFTPS is a free service provided by the Department of the Treasury." When a provider enrolls the client, the employer receives an Inquiry PIN, and Publication 15 says the employer "should activate and use this Inquiry PIN to monitor its account and ensure the third party is making the required tax deposits." The IRS page on outsourcing payroll duties gives the same advice: "Employers should register on the EFTPS system to get their own PIN and use this PIN to periodically verify payments."
If the provider collects client funds into its own account before paying the IRS, ask how long the money sits there, and confirm in EFTPS that each deposit posts to the client's EIN.
The IRS "strongly suggests that the employer does not change their address of record to that of the payroll service provider." Publication 15 explains why: correspondence sent to a third party's address "may significantly limit the employer's ability to be informed about tax matters involving the employer's business." Make the address rule part of onboarding, and ask the provider to confirm it will not file Form 8822-B on the client's behalf.
Switching a client to a new payroll platform means re-entering employee records, year-to-date wages, deductions and state accounts mid-year. A provider that can work inside the platform the client already uses avoids that risk. If the client is choosing a platform at the same time, our comparison of three major payroll platforms for multi-state teams covers the main options.
Remote hiring means a 15-person client can have employees in several states. Ask the provider to walk through what happens when the client hires in a new state: who registers for state withholding and unemployment accounts, who sets up local taxes, and how long it takes. Our guide to multi-state payroll for small businesses lists the state-level items a provider should handle.
The One Big Beautiful Bill Act added new employer reporting for overtime and tips. The 2026 Form W-2 instructions state that "New box 12, code TT, will be used to report the total amount of qualified overtime compensation," that "New box 12, code TP, will be used to report the total amount of cash tips reported to the employer," and that "New box 14b will be used to report the Treasury Tipped Occupation Code(s)." Ask the provider how it captures qualified overtime, reported cash tips and tipped occupation codes during the year, so January is not spent rebuilding the data.
Contractor reporting is often a separate service. If the client pays independent contractors, confirm who collects Forms W-9 and files the 1099s. Our 1099 checklist for accountants covers that workflow.
Because the client stays liable under a PSP or reporting agent arrangement, any cover for penalties has to come from the contract. Look for who pays IRS and state penalties caused by the provider's errors, how fast the provider must notify the client of a missed deposit, and whether interest is covered. Publication 15 warns that if the third party fails to deposit, "the IRS may assess penalties and interest on the employer's account" and that "The employer may also be held personally liable for certain unpaid federal taxes." Our article on the Trust Fund Recovery Penalty explains how that personal liability works.
Ask for the provider's process for releasing payroll registers, tax filings, year-to-date data and state account details if the client leaves. Revoking a Form 8655 and moving deposits to a new agent mid-quarter is a common point for missed or duplicated deposits, so a quarter-end switch is usually safer. Our guide on switching outsourcing providers without losing data covers data handover, and the 30-point provider evaluation checklist covers contract, access and security questions in more depth.
A quarterly review puts these checks into practice. Here is a simple version a firm can run for each payroll client.
A client has three employees, each paid $5,000 a month, so quarterly wages are $45,000. The provider withheld $4,500 of federal income tax in the quarter. Publication 15 states that "The rate of social security tax on taxable wages is 6.2% each for the employer and employee" and that "The Medicare tax rate is 1.45% each for the employee and employer." No employee is near the 2026 Social Security wage base, which Publication 15 gives as $184,500.
| Item | Calculation | Amount |
|---|---|---|
| Federal income tax withheld | From payroll register | $4,500 |
| Social Security (employee and employer) | $45,000 x 12.4% | $5,580 |
| Medicare (employee and employer) | $45,000 x 2.9% | $1,305 |
| Total quarterly liability (Form 941, line 12) | Sum | $11,385 |
| Expected monthly deposit | $11,385 / 3 | $3,795 |
If the four quarters in the lookback period look like this one, the annual total is about $45,540. Publication 15 says that "If you reported $50,000 or less of taxes for the lookback period, you're a monthly schedule depositor," so the client deposits each month's taxes "by the 15th day of the following month."
Now compare the deposits in the client's EFTPS history with the payroll register. Suppose EFTPS shows $3,795 for each of the first two months and nothing for the third. The provider's draft Form 941 still shows $11,385 of liability, so $3,795 is unpaid. The IRS says that "A red flag should go up the first time a service provider misses a payment or makes a late payment." The firm should raise the gap with the provider at once and confirm the deposit posts before the return is filed.
Our Form 941 guide explains the line-by-line review that goes with this check.
Provider quotes are hard to compare because they bundle different things. Some charge a base fee per client plus a fee per employee per pay run. Others charge a flat monthly rate that may exclude year-end forms, new state registrations, off-cycle runs or amended returns. Put every quote on the same basis: annual cost for the client's actual headcount, pay frequency and number of states, including year-end and correction fees. Our guide to outsourced payroll cost per employee sets out the common pricing models in more detail.
Price matters less than the deposit controls above. A cheaper provider that cannot show EFTPS deposits under the client's EIN leaves the client carrying liability it cannot monitor.
Does using a payroll provider make it liable for my client's payroll taxes? Usually not. A payroll service provider or reporting agent works under the client's EIN, and the IRS says the employer remains liable for timely filing and deposits. A certified PEO is the main exception, and agents approved on Form 2678 share liability with the employer.
What is Form 8655 and does my client need one? Form 8655 is the Reporting Agent Authorization. The client signs it to let a provider sign and file certain returns and make deposits electronically. If the provider will file Forms 941 or 940 and make federal deposits, it will normally ask for one.
How can I tell whether a PEO is IRS certified? Check the CPEO public listings on irs.gov. The IRS updates the list each quarter, and the special liability rules apply only to organizations that appear on it.
How often should a firm check a client's EFTPS account? At least once a quarter, before Form 941 is filed, and monthly for clients with larger payrolls or a new provider. The IRS says a single missed or late payment should be treated as a red flag.
If your firm wants support with client payroll processing, reconciliations or year-end W-2 and 1099 preparation while keeping review and client sign-off in-house, contact our team to discuss your payroll workload.
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