CPA for St. Louis, MO Clients: Remote Tax, Payroll and Accounting

Our Naperville, Illinois CPA firm serves St. Louis clients remotely, and we have no office in Missouri. The Mississippi River separates two tax systems here, and many people cross it for work. On the Missouri side, St. Louis adds a city earnings tax that allows no extensions, and the city and county run separate property assessment processes with different dates.

The city earnings tax in practice

The City of St. Louis charges a 1% earnings tax to residents regardless of where their employer is, and to employees of businesses located or working in the city regardless of where they live. The city says the tax makes up 36% of its general revenue. Anyone with a permanent address in the city files on 100% of earnings, including a college student who keeps a city address while attending school elsewhere. People who move in or out part-way through the year owe tax only on wages earned while living or working in the city.

Individual returns (Form E-1) are due April 15, and the city does not allow individuals to extend them. Late tax carries a penalty of 5% of the tax for each month or part of a month, up to 25%. The duty to pay is yours even if an employer fails to withhold.

Nonresidents who work in the city can claim a refund of withheld tax for whole days worked outside it, using Form E-1R. The employer must verify those days, and the city treats a day with any work inside the city as a city day. The refund claim must come within one year of the original due date. The city's page does not address remote work, so keep a calendar of days worked elsewhere.

Employers and the payroll expense tax

Employers withhold the 1% tax from the wages of employees who live or work in St. Louis, and employers also pay a 0.5% payroll expense tax on wages earned in the city. Withholding is reported on Form W-10 and payroll expense tax on Form P-10, due January 31, April 30, July 31 and October 31. The employer page says returns cannot be filed electronically and must be mailed, faxed or emailed, although payment can be made online. Businesses with only an airport location are not subject to the payroll expense tax. Exempt organizations, including hospital and educational entities, send their 501(c)(3) papers to be recorded; the city issues no exemption letter.

Missouri, Illinois and the river commute

For 2025, Missouri's return was due April 15, 2026, with an extended due date of October 15, 2026. The department says the federal deductions for tips, overtime, car loan interest and seniors from the One Big Beautiful Bill cannot be claimed on the Missouri return, and Missouri's single standard deduction was $15,750.

Missouri figures tax as if you were a full-year resident and then reduces it with either a resident credit (Form MO-CR) or a Missouri income percentage (Form MO-NRI), which leaves a prorated liability. The MO-CR form covers income taxes paid to other states or political subdivisions, and it uses tax imposed, not tax withheld.

Illinois follows the same logic in reverse. Its instructions list reciprocal agreements only with Iowa, Kentucky, Michigan and Wisconsin, and they send residents who were taxed by another state to Schedule CR for a credit. A Metro East resident who works in Missouri therefore generally files a Missouri nonresident return and an Illinois return with a credit. A Missouri resident working in Illinois generally files an Illinois nonresident return and claims the MO-CR credit. Whether a city earnings tax counts toward the credit is a question for the instructions of the state that gives it. Our Illinois page covers Illinois rates.

One item is still pending. Missouri's November 3, 2026 ballot carries Amendment 7, which would create a permanent endowment, the Show-Me Prosperity Fund, aimed at eventually eliminating state-imposed taxes. The ballot summary says a yes vote has no immediate impact on taxes, so plan under current law until the result is certified.

Property assessments in the city and county

Missouri law has St. Louis County reassess real property every odd-numbered year, so 2025 was a reassessment year. For 2026 the County Board of Equalization took filings starting May 1, with the deadline on the second Monday in July (July 13, 2026) for both the appeal and its evidence. Hearings were held in July and August by video or telephone, decisions come in the fall, and emailed appeals were not accepted. If you disagree, you may appeal to the Missouri State Tax Commission by September 30 or 30 days after the decision letter, whichever is later. Taxes remain payable while an appeal is pending, and you may pay under protest.

The City of St. Louis Assessor's page says informal appeals are accepted each year from May 1 to June 23; the page is undated, so confirm the dates for the current year. A Board of Equalization appeal must be placed with the Assessor's Office by the second Monday in July, and the board meets from July through the last Saturday in August. A residential owner may represent themselves at the State Tax Commission, but a commercial property owner must have legal representation.

The Indian-American community and US-India tax

St. Louis County, not the city, holds about two thirds of the metro total: about 20,700 residents (2.1%) identify as Asian Indian alone or in any combination, against about 2,600 (0.9%) in the City of St. Louis and about 5,300 (1.3%) in St. Charles County. The bi-state metro area totals about 30,500 (1.1%) (American Community Survey, 2020 to 2024). Missouri and Illinois both fall under the Consulate General of India in Chicago in the Embassy of India's list effective July 15, 2025.

Topics that matter when you file in two states:

• Whether Indian accounts require an FBAR or Form 8938.
• How a foreign tax credit for India-source income fits next to the state credits above.
• How Indian business ownership is reported.
• How an EPF balance is reported.

How we can help

From Naperville we can prepare the federal, Missouri, Illinois and St. Louis returns, help you keep the day-count records a refund claim needs, and set up W-10 and P-10 payroll filings. Bookkeeping, IRS notices and US-India reporting are part of the same remote service. If something in Missouri or Illinois needs a licensed local professional, we will say so.

Frequently asked questions

General information only, not tax, legal or accounting advice for your situation. Rules, limits and deadlines change; confirm the current rules with the official source or a qualified professional before you act. Reading this page does not create a professional relationship with CPA Tax Payroll and Accounting Corp.