Maine tracks the federal April calendar for individuals and corporations, but it handles pass-throughs differently than most states. For the 2025 tax year, individual and C-corporation returns are due April 15, 2026. The detail that trips up preparers new to Maine: there is no separate Maine S-corporation or partnership income return, and Maine has not adopted a pass-through entity tax. What pass-throughs do file is a nonresident withholding return.

What are Maine's 2026 tax filing deadlines?

For the 2025 tax year, the Maine individual return (Form 1040ME) and C-corporation return (Form 1120ME) are due April 15, 2026. Maine discontinued its partnership and S-corporation income returns after 2011, so there is no 1065ME or 1120S-ME to file. The only Maine filing tied to pass-throughs is Form 941P-ME, the nonresident member withholding return, due March 16, 2026.

How does Maine's extension work?

Maine grants an automatic six-month extension to file, to October 15, 2026, with no form required. To avoid the failure-to-pay penalty, you must pay at least 90% of the tax owed by April 15, 2026. The extension covers filing only; interest runs on anything unpaid after the original date.

Does Maine have a pass-through entity tax?

No. Maine has not enacted a pass-through entity tax, so there is no entity-level election to deduct state tax above the federal SALT cap. Maine taxes pass-through income only at the owner level. For clients holding interests in multiple states, state this directly, because a SALT workaround available in a neighboring state does not carry over to Maine.

How does Maine tax nonresident pass-through owners?

The entity withholds. A partnership or S-corporation with Maine-source income and any nonresident members must file Form 941P-ME and withhold Maine tax on each nonresident member's share, at 7.15% for individual members and 8.93% for C-corporation members. Quarterly withholding payments (Form 901ES-ME) are due April 30, July 31, October 31, and January 31. Nonresident members can instead join a composite return.

Who owes Maine estimated tax?

Individuals expecting to owe $1,000 or more in Maine tax after withholding pay quarterly on April 15, June 15, September 15, 2026, and January 15, 2027 (Form 1040ES-ME). The same $1,000 floor and the prior-year liability test both apply.

How does a firm handle Maine at scale?

The mistake to avoid is treating Maine like every other state and queuing a March 15 S-corp or partnership return that does not exist. Map Maine pass-throughs to the 941P-ME withholding return on March 16 and the owner-level returns on April 15, and screen each entity for nonresident members up front because that is what drives the withholding obligation. See how we think about scaling tax prep workflows.

Where do these dates come from?

All deadlines and thresholds here trace to Maine Revenue Services. Verify against the source before filing.