Quarterly Estimated Tax Calculator (2026)

Enter your expected 2026 self-employment income and what you have already paid in. The calculator finds the smallest amount the IRS requires you to pay during the year (the safe harbor), splits it across the four due dates, and tells you what is left to send with each remaining installment.

Who has to pay estimated tax

Federal income tax is pay-as-you-go. Employees pay through withholding; people with 1099, gig or other self-employment income pay four times a year with Form 1040-ES. You generally must pay estimated tax for 2026 if both of these apply (Form 1040-ES, "General Rule"):

1. You expect to owe at least $1,000 in tax after subtracting withholding and refundable credits.
2. Your withholding and refundable credits will be less than the smaller of 90% of your 2026 tax or 100% of your 2025 tax.

"Tax" here means income tax plus self-employment tax, after credits. Below the $1,000 line there is no underpayment penalty, whatever you pay during the year.

The safe harbor: how much is enough

The underpayment penalty is measured against the required annual payment in IRC §6654(d), which is the smaller of:

• 90% of this year's tax, or
• 100% of last year's tax as shown on your 2025 return — 110% if your 2025 adjusted gross income was more than $150,000 ($75,000 if you file separately from your spouse).

Paying that amount in four equal, on-time installments means no penalty, even if the balance due in April is large. Most people with rising income pick the prior-year figure because it is known in January; people whose income has dropped pay 90% of the smaller current-year estimate instead. The calculator uses whichever is lower when you provide last year's tax, and 90% of this year's estimate when you do not.

Due dates for 2026

The periods are not equal quarters: the second installment covers only April and May. You may skip the January payment if you file your 2026 return and pay the full balance by February 1, 2027. A payment mailed by the due date counts as on time by its postmark.

How to pay

• IRS Direct Pay (irs.gov/payments) from a checking or savings account, no fee, no account required — pick "Estimated tax" and the 2026 tax year.
• Your IRS Online Account shows every payment the IRS has recorded, which is the number to enter above as "already paid".
• EFTPS for scheduling all four payments in advance; debit or credit card through an IRS-listed processor (fees apply); or the paper vouchers in Form 1040-ES by mail.
• If you also have a job, raising your W-2 withholding on Form W-4 is an alternative: withholding counts as paid evenly through the year no matter when it is taken.

If you missed or underpaid an installment

The penalty is interest on the shortfall, installment by installment, from its due date until it is paid (Form 2210), at the federal underpayment rate. It is not a flat fine, so paying as soon as you notice stops it growing. If your income arrived unevenly — most of it late in the year — the annualized income method on Schedule AI of Form 2210 can reduce or remove the penalty for the earlier installments. This calculator assumes even income and does not compute the penalty.

State estimated payments

Most states with an income tax want their own estimated payments, usually on the same four dates but with different thresholds (for example, more than $500 owed in Ohio and Georgia; $1,000 in North Carolina; $300 in New York) and their own safe-harbor rules. The schedule above shows one quarter of your expected state tax as a starting point; the state pages list each state's threshold and payment form.

California is the notable exception to equal quarters: the Franchise Tax Board requires 30% of the year's estimated tax by April 15, 40% by June 15, nothing in September and the last 30% by January 15 (Form 540-ES). A Californian paying a flat quarter each time is short by June and owes a penalty on the difference.

What this calculator does not cover

• The farming and fishing rule (67% instead of 90%), household employment taxes, the net investment income tax and the alternative minimum tax.
• The annualized installment method for uneven income, and the penalty itself.
• Itemized deductions, self-employed health insurance and retirement contributions — each lowers the tax, so the figure here is a conservative estimate. The main calculator lists everything included.

Data status

Federal 2026 parameters, including the §6654 safe-harbor figures: verified · last verified 2026-09-05 · sources: IRC §6654 and the 2026 Form 1040-ES instructions. See the methodology for the full list.