Yes. Missouri accepts a federal tax extension automatically, so if the IRS granted you more time to file through Form 4868, your Missouri return deadline shifts from April 15, 2026, to October 15, 2026, without a separate state application.1Missouri Revisor of Statutes. Missouri Revised Statutes RSMo Section 143.551 The one catch: the extension covers filing only. Any tax you owe is still due April 15.
How the Automatic Acceptance Works
Section 143.551 of the Missouri Revised Statutes gives any taxpayer with a federal filing extension a matching state extension by operation of law.1Missouri Revisor of Statutes. Missouri Revised Statutes RSMo Section 143.551 You do not file a Missouri extension form, pay a fee, or wait for Department of Revenue approval. The federal paperwork does all the work on the state side.
You do have one obligation. When you eventually file your Missouri return, include a copy of your federal Form 4868. Tax software handles this automatically for electronic filers; paper filers need to physically attach it. The Department of Revenue’s FAQ warns that missing this documentation can cause processing delays or a dispute over whether you filed on time.2Missouri Department of Revenue. FAQs – Individual Income Tax
For the 2025 tax year, the standard filing deadline is April 15, 2026, and the extended deadline is October 15, 2026. Both dates fall on weekdays, so there’s no weekend or holiday shift this year.3Missouri Department of Revenue. 2026 Tax Calendar
Your Payment Is Still Due April 15
This is where most people get into trouble. A filing extension is not a payment extension. Section 143.551(4) states that if your filing deadline is extended but your payment deadline is not, the tax is still owed by the original date.1Missouri Revisor of Statutes. Missouri Revised Statutes RSMo Section 143.551 For 2026, that means April 15, even though your return itself isn’t due until October.
If you don’t know your exact liability yet, estimate it and pay what you can. Underpaying beats paying nothing, because penalties and interest are calculated on the unpaid balance. Every dollar you send by April 15 reduces your exposure. The Department of Revenue accepts online payments by eCheck or credit and debit card.4Missouri Department of Revenue. Pay Individual Income Taxes Online
One narrow exception exists. If the IRS granted you a federal extension for payment (not just filing), Missouri automatically extends your state payment deadline too under Section 143.551(3).1Missouri Revisor of Statutes. Missouri Revised Statutes RSMo Section 143.551 Federal payment extensions are rare and require showing undue hardship to the IRS. If you have one, send a copy to the Department of Revenue to get the same treatment at the state level.
What It Costs to Miss the Payment Deadline
Missouri treats late filing and late payment as separate violations with separate penalties. With an extension in place, the one you need to worry about is the payment penalty.
The failure-to-pay penalty is a flat 5% of the unpaid balance.2Missouri Department of Revenue. FAQs – Individual Income Tax It’s a one-time charge, not a monthly accrual.
On top of the penalty, interest runs on the unpaid balance from the original April 15 due date until you pay. For 2026 the statutory interest rate is 7%.5Missouri Department of Revenue. Statutory Interest Rates Interest accrues regardless of your extension.
The failure-to-file penalty is harsher: 5% of unpaid tax for the first month, plus 5% for each additional month the return stays unfiled, capped at 25%.6Missouri Revisor of Statutes. Missouri Revised Statutes RSMo Section 143.741 A valid extension keeps you out of this penalty entirely, as long as you file by October 15. And because the penalty applies only to tax that remains unpaid at the due date, taxpayers who paid in full by April 15 face no filing penalty even if they file late without an extension.
If You Don’t Have a Federal Extension
Taxpayers who want more time for Missouri but haven’t filed federally use Form MO-60, the Application for Extension of Time to File.7Missouri Department of Revenue. Form MO-60 – Application for Extension of Time to File The form must be mailed to the Department of Revenue by April 15. Miss that date and you lose the extension entirely.
Form MO-60 asks for your Social Security number and your estimated Missouri tax liability. If you owe, include a check or money order with the form. When you later file your return, attach a copy of the MO-60. There’s no electronic submission; the form goes to Missouri Department of Revenue, P.O. Box 3400, Jefferson City, MO 65105-3400.8Missouri Department of Revenue. Form MO-60 – 2025 Application for Extension of Time to File The state extension under MO-60 cannot exceed six months, matching the federal limit, though taxpayers living outside the United States can receive a longer extension at the director of revenue’s discretion.1Missouri Revisor of Statutes. Missouri Revised Statutes RSMo Section 143.551
Combat Zone Service
Military members serving in a combat zone or contingency operation get a different rule. The filing deadline is automatically extended 180 days after you leave the combat zone or end qualifying service, plus credit for however many days remained on your original filing deadline when you entered.9Missouri Department of Revenue. Military Reference Guide If you deployed on April 1, two weeks before the April 15 deadline, you get 180 days plus those 14 remaining days after you return. Service members who entered the combat zone before the filing period began preserve the entire filing period. These extensions cover filing returns, paying taxes, and submitting refund claims.