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 Alabama estimated tax?
In most cases, you must pay estimated tax for 2026 if both of the following apply: 1. You expect to owe at least $500 in tax for 2026, after subtracting your withholding and credits. 2. You expect your withholding plus your credits to be less than the smaller of: a. 90% of the tax to be shown on your 2026 tax return, or b. 100% of the tax shown on your 2025 tax return (2025 return must cover all 12 months).
How do you avoid a Alabama underpayment penalty?
Smaller of 90% of 2026 tax or 100% of 2025 tax (12-month return); substitute 110% for 100% if 2025 Alabama AGI was more than $150,000 ($75,000 if 2026 filing status is married filing separately). Farmers have special rules.
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. Alabama figures its own tax, so the state amount is separate.