Minnesota tracks the federal calendar on filing dates but grants corporations a longer automatic extension than the federal six months. It has high graduated rates, an active elective PTE tax, and a distinctive surtax on large investment income.
Minnesota Tax Deadlines at a Glance (2026)
Entity Type | Return Due | Extended Due Date |
|---|---|---|
Individuals (M1) | April 15, 2026 | October 15, 2026 |
C Corporations (M4) | April 15, 2026 | November 15, 2026 (7-month) |
S Corporations (M8) | March 16, 2026 | September 15, 2026 |
Partnerships (M3) | March 16, 2026 | September 15, 2026 |
The correction to note: Minnesota grants corporations an automatic 7-month extension to November 15, not the six-month October date. S corporations (M8) and partnerships (M3) follow the federal March 16, 2026 deadline (rolled from Sunday, March 15) and get a 6-month extension to September 15. All Minnesota extensions are automatic — no form — but tax is due by the original date.
Rates and the Elective PTE Tax
Minnesota’s individual income tax is steeply graduated: 5.35%, 6.80%, 7.85%, and a 9.85% top rate. The corporate franchise tax is 9.8% plus a minimum fee. Minnesota’s elective pass-through entity tax is levied at the top individual rate, 9.85%, and is active through the 2027 tax year; the election is made on Schedule PTE by the entity’s extended due date and is irrevocable.
The Net Investment Income Tax Surtax
Effective for 2024 and later, Minnesota imposes a 1% Net Investment Income Tax (NIIT) surtax on net investment income above $1,000,000 for individuals, estates, and trusts, reported on Schedule NIIT. CPAs should model this for high-net-worth clients with large investment portfolios or one-time gains.
Estimates, Extensions, and Penalties
Individual estimated payments are due April 15, June 15, September 15, 2026, and January 15, 2027. Because extensions are automatic, no form is needed — but interest and late-payment penalties apply to tax not paid by the original date. The 2026 interest rate is 7%; individual late-payment penalty is 4% of unpaid tax.
CPA Action Steps
Use the 7-month corporate extension to November 15
File M8 and M3 by March 16 (weekend roll from March 15)
Model the 1% NIIT surtax over $1M in investment income
Consider the 9.85% PTE election for SALT-cap relief
Verify current rates and dates against the Minnesota Department of Revenue (revenue.state.mn.us) before filing.