Missouri keeps every return type on one date. For the 2025 tax year, individual, C-corporation, S-corporation, and partnership returns are all due April 15, 2026. Missouri does not follow the federal March date for pass-throughs, which is the detail most likely to get mis-filed in a multistate workflow. The state also offers a SALT Parity election worth flagging before the deadline.

What are Missouri's 2026 tax filing deadlines?

For the 2025 tax year, the Missouri individual return (MO-1040), C-corporation return (MO-1120), S-corporation return (MO-1120S), and partnership return (MO-1065) are all due April 15, 2026, the 15th day of the fourth month. Missouri's pass-through information returns share the individual date, not the federal March 15 schedule.

How does Missouri's extension work?

Missouri grants an automatic extension to October 15, 2026 and honors the federal extension, so no Form MO-60 is needed if you have an approved federal extension and do not expect to owe. File MO-60 if you owe Missouri tax or want a state extension without a federal one. The extension is to file only; pay by April 15, 2026 to avoid additions to tax.

What is Missouri's SALT Parity (MO-PTE) election?

Missouri lets an S-corporation or partnership elect to pay state tax at the entity level under the SALT Parity Act, which moves the deduction above the federal SALT cap. The election is available for 2025, made annually on Form MO-PTE, and is irrevocable once made for the year. The entity-level rate is 4.7%, matching the top individual rate, and members claim a credit for their share of the tax paid.

How does Missouri tax nonresident pass-through owners?

The entity handles nonresident owners one of three ways: it withholds Missouri tax and files Form MO-1NR with MO-2NR, it files a composite return covering those owners, or the owner signs a Form MO-3NR agreement to file individually. The withholding or composite obligation is due with the entity return.

Who owes Missouri estimated tax?

Individuals expecting a Missouri liability of $100 or more not covered by withholding pay quarterly on April 15, June 15, September 15, 2026, and January 15, 2027 (Form MO-1040ES). Corporations expecting to owe $250 or more make quarterly payments computed at the 4% corporate rate.

How does a firm handle Missouri at scale?

The trap is the pass-through date. The federal 1065 and 1120-S are due in March, but Missouri's MO-1065 and MO-1120S are due April 15, so a workflow keyed to the federal date will mis-date the Missouri returns. Set the uniform April 15 date as Missouri-specific, decide the MO-PTE election before filing, and screen each entity for nonresident owners. See how we think about scaling tax prep workflows.

Where do these dates come from?

All deadlines and thresholds here trace to the Missouri Department of Revenue. Verify against the source before filing.