St. Louis Form P-10 Payroll Expense Tax Return: Filing, Deadlines, and Penalties

The St. Louis Form P-10 is the quarterly return employers use to report and pay the city’s payroll expense tax: 0.5% of the gross compensation paid to employees for work performed inside city limits. The tax falls on the employer, not the employee, and it is separate from the 1% individual earnings tax the city also collects. You cannot e-file the P-10. The completed form goes to the Collector of Revenue by mail, fax, or email, though payment can be made online.

Who Files a P-10

Any business with employees performing work inside the geographic boundaries of St. Louis owes the payroll expense tax, regardless of entity type. Payments to independent contractors are not part of the P-10 calculation; contractors and self-employed individuals report the separate 1% earnings tax on Form E-234.¹

Religious and charitable organizations, nonprofit civic, social service, and fraternal organizations, nonprofit hospitals and educational institutions, and State of Missouri and United States government agencies are exempt. Exempt employers should still send a copy of their 501(c)(3) letter or other nonprofit documentation to the Earnings Tax Department so the city can verify the status.²

One geographic note worth flagging: businesses located exclusively at St. Louis Lambert International Airport do not owe the tax. The city owns the airport, but it sits outside the city boundaries, so employees working only there are not covered.³

Filing requires an earnings tax account with the Collector of Revenue. If you don’t yet have one, submit Form E-9 to the Earnings Tax Department by fax, email, or mail; your account number is simply your FEIN or SSN.⁴

What Counts as Gross Compensation

The tax base is broader than federal taxable wages. Start with total wages, salaries, commissions, and bonuses, and then add back several pre-tax items the city specifically treats as taxable:

Cafeteria plan contributions (IRC Sections 125–129)
Deferred compensation such as 401(k), 403(b), and 457 plan contributions (IRC Sections 401, 403, 414, 457, 501)
Health Savings Account contributions
Prepaid medical premiums
Additional medical or dental insurance purchases

You cannot reduce taxable payroll by what employees contribute to retirement plans or health coverage. The gross compensation figure on your P-10 will be higher than the taxable wages shown on most federal forms.⁵

Employees Who Work Partly Outside the City

The payroll expense tax reaches only wages earned inside St. Louis. For an employee who splits time between a city office and a location outside city limits, report only the portion of pay tied to work performed in the city. The city’s rule for the related withholding tax treats any portion of a day worked within St. Louis as a full city workday, and the same logic applies to the P-10.²

Employees who work entirely outside the city generally do not belong on the P-10, even if your business is headquartered in St. Louis. The tax follows where the work happens, not where the employer sits.⁶

Filling Out the Form

Download the fillable P-10 from the Collector of Revenue’s website. It is combined with the W-10 employer withholding return, so you’ll see fields for both taxes on one document.⁷

At the top, enter your business name, address, and account number (your FEIN or SSN), and select the quarter you are reporting. In the P-10 section, enter the total gross compensation paid for work performed in St. Louis during the quarter, with the pre-tax add-backs listed above. Multiply that figure by 0.005 to calculate the tax owed and enter the result on the tax-due line. If you have credits or adjustments from a prior quarter, enter them in the designated field and subtract to arrive at the final amount due.

How to Submit and Pay

Send the completed P-10 to the Collector of Revenue by one of the following:

Mail: Gregory F.X. Daly, Collector of Revenue, 1200 Market Street, Room 410, St. Louis, MO 63103
Fax: (314) 622-4847
Email: EarningsTaxCOR@stlouis-mo.gov

Payment can travel with a mailed return or go through the city separately. By mail, use a personal check, cashier’s check, or money order payable to the Collector of Revenue. In person at Room 410 of City Hall, you can pay by credit card, debit card, cash, personal check, cashier’s check, or money order. Online payment runs through payitSt.Louis; credit and debit payments carry a 2.45% processing fee, and ACH payments have a flat $1.25 fee per transaction. If you pay online, you still need to file the form itself by mail, fax, or email, because the portal handles payment only.⁸⁹

Quarterly Deadlines

The form and payment are due at the end of the month following each quarter:

First quarter (January–March): April 30
Second quarter (April–June): July 31
Third quarter (July–September): October 31
Fourth quarter (October–December): January 31

There is no separate annual reconciliation for the payroll expense tax. The four quarterly P-10 filings are the full obligation. The W-3 reconciliation applies to employer withholding, not to the payroll expense tax.¹⁰

Penalties and Interest for Late Filing

Missing a quarterly deadline triggers both a penalty and interest. The penalty is 5% of the unpaid tax for each month or partial month the return is late, capped at 25%. Interest accrues at 1% per month (12% annually) until the balance is paid in full. Both charges run against the unpaid amount, so filing on time with a partial payment limits what you owe compared with not filing at all. If a deadline has already slipped, file and pay as soon as you can to keep the monthly charges from stacking further.²

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City of St. Louis. Earnings Tax Forms and Documents
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City of St. Louis. Employer Withholding and Payroll Expense Tax Information
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City of St. Louis. Business Earnings Tax Information
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City of St. Louis. Open an Earnings Tax Account
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City of St. Louis. Taxable and Non-Taxable Items
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City of St. Louis. Individual Earnings Tax Information
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City of St. Louis. W-10/P-10 Forms (Fillable)
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City of St. Louis. File Individual Earnings Taxes
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City of St. Louis. Make a Payment to the Collector of Revenue
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City of St. Louis. Earnings Tax Department