Missouri largely conforms to the federal filing calendar, with one important exception: its pass-through returns are due in April, not on the federal March date. The state also offers an elective PTE tax and has two city earnings taxes CPAs must watch.
Missouri Tax Deadlines at a Glance (2026)
Entity Type | Return Due | Extended Due Date |
|---|---|---|
Individuals (MO-1040) | April 15, 2026 | October 15, 2026 |
C Corporations (MO-1120) | April 15, 2026 | October 15, 2026 |
S Corporations (MO-1120S) | April 15, 2026 | October 15, 2026 |
Partnerships (MO-1065) | April 15, 2026 | October 15, 2026 |
The correction to note: MO-1120S and MO-1065 are due April 15, 2026 — the 15th day of the 4th month — not the federal March 16. Missouri does not follow the federal March pass-through deadline; both extend to October 15 with a federal extension.
Rates and the SALT Parity PTE Tax
Missouri’s top individual income tax rate is 4.7% for the 2025 tax year (further cuts are trigger-based on revenue growth, not calendar-fixed). The corporate income tax rate is a flat 4.0%. Under the SALT Parity Act, S corporations and partnerships may make an annual, irrevocable election to pay tax at the entity level (Form MO-PTE, which is paper-file only), giving members a credit for their share — a federal SALT-cap workaround.
Local Earnings Taxes
Missouri has no general local income tax, but two cities impose a 1% earnings tax: Kansas City and St. Louis. Residents pay on all income; nonresidents pay on income earned within city limits, and businesses on net profits. This is a common miss for clients living or working in either city — screen for it during return prep.
Estimates, Extensions, and Penalties
Individual estimated payments are due April 15, June 15, September 15, 2026, and January 15, 2027. Missouri’s extension is automatic if you have a federal extension and owe no additional tax; if you owe, file Form MO-60 with payment by April 15. An extension covers filing only. The 2026 statutory interest rate is 7%, and the standard failure-to-file addition is 5% per month (max 25%).
CPA Action Steps
File MO-1120S and MO-1065 in April, not on the federal March date
Use 4.7% (2025) individual / 4.0% corporate; further individual cuts are trigger-based
Remember Form MO-PTE is paper-file only
Screen clients for the Kansas City and St. Louis 1% earnings taxes
Verify current rates and dates against the Missouri Department of Revenue (dor.mo.gov) before filing.