Common paymaster rules for related corporations

The rule in the publication

Publication 15-A (2026) describes the arrangement in three short paragraphs. Related corporations sometimes share workers, for example an executive who is on the payroll of a parent and a subsidiary at the same time. Without special treatment each corporation would be a separate employer, and each would withhold and match social security tax on the wages it paid up to the annual wage base. The common paymaster rule fixes that. When the individual works for two or more related corporations at the same time and the pay comes through a common paymaster that is itself one of the corporations, the group is considered a single employer for this purpose, and it pays in total no more social security tax than a single employer would.

A worked example with the 2026 wage base

The 2026 social security wage base is $184,500, and the rate is 6.2% for the employee and 6.2% for the employer (both figures appear in Publication 15-A (2026)). Suppose an executive is paid $120,000 by corporation A and $120,000 by corporation B in 2026. Treated as two employers, each corporation is below the wage base on its own, so tax applies to $240,000 of wages: $14,880 withheld and $14,880 matched, $29,760 in total. Treated as one employer through a common paymaster, tax applies only to the first $184,500: $11,439 withheld and $11,439 matched, $22,878 in total. The difference is $6,882 in combined employee and employer tax. The calculator above does this arithmetic for any pair of wage amounts.

Two cautions. The example is arithmetic built on the publication’s rule and its 2026 figures, not an example the IRS prints, and it assumes the corporations qualify. Also, Medicare tax has no wage base, so the common paymaster rule saves nothing there: all $240,000 is Medicare wages either way.

What each corporation still does

The single-employer treatment is narrow. The publication says each corporation must pay its own part of the employment taxes and may deduct only its own part of the wages. The deductions are not allowed unless the corporation reimburses the common paymaster for the wage and tax payments. In practice that means the paymaster needs a paper trail showing what it paid for each corporation and what each corporation paid back.

The common paymaster is responsible for filing information and tax returns and issuing Forms W-2 with respect to the wages it is considered to have paid as a common paymaster. That is a real administrative burden: the paymaster files for the wages it is considered to have paid, so the corporations should coordinate to avoid reporting the same wages twice.

A checklist before relying on it

The publication supplies the test in plain terms, and each item must be true. First, the employers are corporations, and they are related. Second, they employ the same individual at the same time, not one after the other. Third, the pay is made through a common paymaster, and the paymaster is one of those corporations rather than an outside payroll vendor. Fourth, the corporations reimburse the paymaster, because the wage deduction depends on it. The publication points to Regulations section 31.3121(s)-1 for the details, including what makes corporations related, and that regulation is where a tax professional will look.

Notice what the rule does not say. It does not let one corporation pay another’s employees without a reimbursement trail, and it does not apply to unrelated companies or to an outside staffing vendor. Other third-party payer arrangements, such as an agent with an approved Form 2678 or a reporting agent, are described in the same section of the publication and work differently.

Tax-exempt organizations and FUTA

One related point appears in section 3 of the publication. A section 501(c)(3) organization is exempt from FUTA tax, and that exemption cannot be waived. But it becomes subject to FUTA tax when it pays wages on behalf of a non-501(c)(3) organization, and the publication lists a 501(c)(3) organization acting as a common paymaster for a non-501(c)(3) organization as one such case. So a nonprofit that acts as paymaster for a taxable affiliate should not assume the nonprofit exemption follows the wages.

What this page does not decide

Whether your corporations are related, whether the wages are properly attributed, and whether the reimbursement arrangement is documented well enough are fact questions. For a live arrangement, a payroll provider or a CPA who has read the regulation should confirm it. This page explains the publication’s rule and runs the wage base arithmetic, nothing more.

Sources

• IRS Publication 15-A, Employer’s Supplemental Tax Guide (2026): section 7, Special Rules for Paying Taxes: Common Paymaster. Read November 2, 2026.

Edition read: Publication 15-A (2026), for use in 2026. Rates, wage bases and dollar limits on this page are the 2026 figures printed in that edition; check the current publication and the IRS employment tax pages for your tax year. This page summarizes the publication and does not replace it.