# Quarterly estimated tax calculator (2026)

> Free 2026 estimated tax calculator: the Form 1040-ES safe-harbor amount (90% of this year or 100%/110% of last year) split into four payments, with the 2026 due dates.

Canonical page: https://superbooks.io/tools/estimated-tax-calculator/

Pay at least the smaller of 90% of your 2026 tax or 100% of your 2025 tax (110% if your 2025 adjusted gross income was over $150,000) through withholding and four estimated payments: April 15, June 15 and September 15, 2026, and January 15, 2027.

Formula: Safe harbor = the smaller of 90% × expected 2026 tax and 100% × 2025 tax (110% when 2025 AGI was over $150,000, or $75,000 married filing separately). Estimated tax to pay = safe harbor − withholding, in four equal payments; none is required if you expect to owe less than $1,000 after withholding and refundable credits.

GET https://app.superbooks.io/api/tools/estimated-tax

## Sources (last checked 2026-10-21)

- [IRS Form 1040-ES (2026), Estimated Tax for Individuals](https://www.irs.gov/pub/irs-pdf/f1040es.pdf)

Informational estimate, not tax advice. SuperBooks does not prepare or file tax forms.

## Questions

### When are 2026 estimated tax payments due?

April 15, 2026, June 15, 2026, September 15, 2026 and January 15, 2027. If a date falls on a Saturday, Sunday or legal holiday, a payment made the next day that is not one is on time.

### Who has to pay estimated tax for 2026?

In most cases, you do if you expect to owe at least $1,000 for 2026 after withholding and refundable credits, and you expect your withholding and refundable credits to be less than the smaller of 90% of your 2026 tax or 100% of your 2025 tax.

### When does the 110% rule apply?

When your 2025 adjusted gross income was more than $150,000, or more than $75,000 if your filing status for 2026 is married filing separately. Then 110% of your 2025 tax replaces 100%.