Enterprise
Individual & Small Business
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Federal 2026 estimated tax due dates, for comparison: April 15, 2026, June 15, 2026, September 15, 2026, January 15, 2027.
Who must pay Maine estimated tax?
In most cases, you must pay estimated tax if your estimated Maine income tax for the year, over and above tax withheld and allowable credits, is $1,000 or more and if your tax liability for the prior year was also $1,000 or more. (Text from the 2025 Form 1040ES-ME; 2026 edition not retrievable.)
How do you avoid a Maine underpayment penalty?
To avoid penalties, estimated tax paid must be no less than the smaller of: the preceding year's tax liability (if a 12-month year) or 90% of the current-year liability (66 2/3% farmers/fishermen). No 110% rule. Special rule: 'unusual event income' (e.g., a large one-time gain) requires 90% of the tax on that income in the installment period received and the prior-year rule cannot be used for it.
How much should you pay?
Start with your federal estimate: the free Quarterly Estimated Tax Calculator works out your 2026 federal payments and safe harbor. Maine figures its own tax, so the state amount is separate.