Estimated Quarterly Tax Calculator for 2026

Generally, you must pay estimated tax for 2026 if you expect to owe at least $1,000 in tax for 2026 after subtracting your withholding and refundable credits, and you expect your withholding and refundable credits to be less than the smaller of: 90% of the tax to be shown on your 2026 tax return, or 100% of the tax shown on your 2025 tax return (110% if your AGI was over $150,000).

For the 2026 tax year, payments are typically due on April 15, 2026; June 15, 2026; September 15, 2026; and January 15, 2027.

The safe harbor rule is a way to avoid underpayment penalties. It requires you to pay at least 90% of your current year's tax liability or 100% of your previous year's tax liability (110% if your Adjusted Gross Income was over $150,000), whichever is smaller. By meeting this threshold through withholding and estimated payments, you can avoid penalties even if you still owe money at the end of the year.

Self-employment tax consists of Social Security and Medicare taxes. For 2026, it's calculated on 92.35% of your net earnings from self-employment. The rate is 12.4% for Social Security up to the annual limit and 2.9% for Medicare with no limit. This calculator handles the basic calculation for you.

Yes, you can and should adjust your estimated tax payments if your income, deductions, or credits change significantly during the year. You can re-calculate your estimated tax and adjust the remaining quarterly payments accordingly.

If you don't pay enough tax throughout the year, you may have to pay an underpayment penalty. The penalty is calculated based on the amount of the underpayment, the period when the underpayment was due, and the interest rate for underpayments that the IRS publishes quarterly.