Maine grants automatic six-month extensions and tracks the federal calendar on most dates, but its pass-through extension differs from the federal one, and — notably — Maine had no elective pass-through entity tax for the 2025 tax year.

Maine Tax Deadlines at a Glance (2026)

The correction to note: Maine’s pass-through filing (Form 941P-ME) is due March 16, 2026 (March 15 is a Sunday), but its automatic extension runs to October 15, 2026 — not the federal September 15. Individuals and C corporations file by April 15 with an automatic six-month extension to October 15, provided at least 90% of tax is paid by the original date.

Pass-Throughs and the (Missing) PTE Tax

Maine has no separate S-corporation or partnership income tax return; pass-throughs with nonresident members file Form 941P-ME for nonresident withholding and may elect a composite return. Importantly, Maine did not have an elective PTE tax for the 2025 tax year — the new PTE tax and credit (LD 191) first applies to tax years beginning in 2026. Do not assume a Maine SALT-cap workaround was available for 2025.

Rates

Maine’s individual income tax is graduated at 5.8%, 6.75%, and a 7.15% top rate. The corporate income tax is graduated from 3.5% up to an 8.93% top rate (on income over $250,000). Maine’s corporate extension is a six-month automatic extension — not seven months — with tax due at the original date.

Estimates, Extensions, and Penalties

Individual estimated payments are due April 15, June 15, September 15, 2026, and January 15, 2027, with a safe harbor of 90% current-year or 100% prior-year. The 2026 interest rate is 9%, compounded monthly. Extensions cover filing only; pay 90% by the original date to avoid penalties.

CPA Action Steps

• Note the pass-through extension is October 15, not September 15

• File Form 941P-ME for nonresident withholding; Maine has no separate PTE income return

• Don’t rely on a Maine PTE election for 2025 — it first applies in 2026 (LD 191)

• Use the six-month (not seven-month) corporate extension

Verify current rates and dates against Maine Revenue Services (maine.gov/revenue) before filing.