What happens if I file my federal return after April 15?

If you owe tax and file after April 15 without an approved extension, the IRS assesses a failure-to-file penalty (5% of unpaid tax per month, up to 25%) plus a failure-to-pay penalty (0.5% per month) plus interest. If you're due a refund, there's no late-filing penalty — but you have only three years from the original deadline to claim it. CPAs should advise extension filers that an extension extends time to file, never time to pay.

Do state filing deadlines automatically follow federal?

Most states conform to the federal April 15 individual deadline, but conformity varies for corporate, pass-through, and franchise filings. Several states have unique deadlines: Louisiana (May 15), Virginia (May 1), Iowa (May 1 for individual), Delaware (April 30 for individual). Always verify against the state revenue department site — TaxScout links to the authoritative source on every state page.

Are estimated quarterly payments mandatory for CPA-firm clients?

Federally, individuals must pay estimated tax if they expect to owe $1,000 or more after withholding. C-corporations have a $500 threshold. Underpayment triggers Form 2210 / 2220 penalties calculated quarterly. Most CPA firms advise clients to safe-harbor at 100% of prior-year liability (110% for AGI over $150K) to avoid the penalty entirely.

Tax Year 2026 · Filed 2027State-revenue-department verified

Michigan tax deadlines 2026

Last updated May 13, 2026

Michigan flat individual income tax rate is 4.25% (4.05% temporarily in 2024 then reverted).
Form MI-1040 conforms to federal April 15. Automatic 6-month extension via federal Form 4868 — no separate MI extension form.
Detroit and several other Michigan cities levy local income taxes — filed separately on city-specific forms.

Michigan individual income tax (Form MI-1040)

Filing deadline

April 15, 2027

Extension deadline

October 15, 2027

Michigan imposes a flat 4.25% individual income tax. Automatic 6-month extension follows federal — no separate MI extension form needed if federal Form 4868 is filed.

Quarterly payments

Q1 2026

Jan 1 – Mar 31, 2026

April 15, 2026

Q2 2026

Apr 1 – May 31, 2026

June 15, 2026

Q3 2026

Jun 1 – Aug 31, 2026

September 15, 2026

Q4 2026

Sep 1 – Dec 31, 2026

January 15, 2027

Authoritative source

Michigan Flow-Through Entity Tax (FTE)

Filing deadline

March 16, 2027

Michigan FTE election (Form 5772) at 4.25% provides federal SALT cap workaround for partnerships and S-corps. Annual election required; quarterly estimated payments aligned with federal estimated dates.

Authoritative source

City of Detroit individual income tax

Detroit residents owe 2.4% local income tax; non-residents earning in Detroit owe 1.2%. Filed on Form D-1040 (resident) or D-1040(NR). Annual return due April 15.

Authoritative source

Federal individual income tax (Form 1040)

Filing deadline

April 15, 2027

Extension deadline

October 15, 2027

Quarterly payments

Q1 2026

Jan 1 – Mar 31, 2026

April 15, 2026

Q2 2026

Apr 1 – May 31, 2026

June 15, 2026

Q3 2026

Jun 1 – Aug 31, 2026

September 15, 2026

Q4 2026

Sep 1 – Dec 31, 2026

January 15, 2027

Authoritative source

Authoritative resources

File these Michigan returns with confidence

TaxScout's tax form library walks through every IRS form CPA firms file for Michigan clients — who must file, key fields, common mistakes, and step-by-step instructions.

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Frequently Asked Questions

Michigan-specific and federal questions for tax year 2026.

Yes. Detroit and ~22 other Michigan cities (including Flint, Grand Rapids, Lansing, Pontiac, Saginaw) impose local income taxes. Most levy 1% on residents and 0.5% on non-residents earning in the city; Detroit charges 2.4% residents / 1.2% non-residents. Each city has its own filing form (e.g., Detroit D-1040). Annual returns due April 15.

Multi-state filing without the spreadsheet

TaxScout tracks every client's state filing dates, sends automated reminders, and surfaces missing documents before deadlines hit.

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