Maine

Corporate income tax

Form 1120ME is due on the same date as the federal corporate return: the 15th day of the fourth month after the end of the tax year, without regard to federal extension. Graduated rates 3.5% (up to $350,000) to 8.93% (over $3,500,000).

Extension. Automatic six-month extension to file; no Maine extension form required

Partnerships and S corporations

Nonresident-member withholding regime (941P-ME) plus optional composite return. Secondary sources (Wipfli; a July 2026 tax blog) report Maine enacted an elective pass-through entity tax effective for tax years beginning Jan 1, 2026 (entity rate 7.15%, 90% owner credit); this could NOT be confirmed on any Maine Revenue Services page as of 2026-09-01.

Sales and use tax

Due date. Returns are due on the 15th day of the month following the end of the reporting period (next business day if the 15th is a weekend or state holiday).

Filing frequency. MRS assigns monthly, quarterly, semiannual or annual filing based on average tax liability (MRS Rule 304); accounts are reviewed annually and taxpayers are notified of changes.

Thresholds. Monthly: average liability $600 or more per month. Quarterly: at least $100 but less than $600 per month. Semiannual: less than $100 per month but more than $50 per year. Annual: less than $50 per year.

Notes

Maine has no corporate minimum tax, no general franchise tax and no separate partnership/S-corp income tax return; the pass-through filing is the 941P-ME withholding return. Sales tax returns are due the 15th (earlier than the 20th used by most states).