Michigan’s calendar has a distinctive corporate date and an often-missed entity-level option. The Corporate Income Tax return is due April 30 — the last day of the fourth month — and Michigan taxes pass-throughs at the entity level only if they elect its Flow-Through Entity Tax.

Michigan Tax Deadlines at a Glance (2026)

Two corrections CPAs should note. First, the Corporate Income Tax return is due April 30, 2026 — the last day of the 4th month — not April 15. Second, Michigan does not impose a state return on S corporations and partnerships in the ordinary case; their income flows through to owners’ MI-1040s. The only Michigan entity-level pass-through return is the elective Flow-Through Entity Tax.

The Flow-Through Entity (FTE) Tax

Michigan’s elective Flow-Through Entity Tax (Form 5772) is a SALT-cap workaround at the 4.25% individual rate. Owners receive a refundable Michigan credit for their share. The annual FTE return is due March 31, 2026 (extendable six months to September 30). Note a recent change: under PA 216 of 2024, the election deadline is now the last day of the 9th month (September 30) for calendar-year filers — many older articles still cite the old March 15 date. The election binds three tax years.

Rates and City Taxes

Michigan’s individual income tax is a flat 4.25% for 2025 and 2026 (the 2023 temporary drop to 4.05% has reverted). The Corporate Income Tax is 6.0%, with no filing required if apportioned gross receipts are under $350,000. A frequently-missed layer: 24 Michigan cities levy a local income tax — Detroit at 2.4% resident / 1.2% non-resident, Grand Rapids and Saginaw at 1.5% / 0.75%, and others at 1% / 0.5%. Detroit’s is filed with the state; most others directly with the city.

Estimates, Extensions, and Penalties

Individual estimated payments (MI-1040ES) are due April 15, June 15, September 15, 2026, and January 15, 2027. A federal extension gives an automatic Michigan extension to October 15 for individuals; businesses file Form 4 with a tentative payment. Extensions cover filing, not payment. Late penalties begin at 5% plus 5% per month; interest floats at the prime rate plus 1%, reset each January and July.

CPA Action Steps

• Use April 30 for the C-corp CIT return — not April 15

• Don’t imply a Michigan March pass-through return; add the elective FTE tax (Form 5772, due March 31)

• Note the FTE election deadline is now September 30 (PA 216 of 2024)

• Track the 24 city income taxes for affected clients

Verify current rates and dates against the Michigan Department of Treasury (michigan.gov/taxes) before filing.