Estimated Tax Penalty Calculator (2026)
Enter the year's federal tax, your withholding and the estimated payments made by each due date. The calculator shows which installments were short, the underpayment charge accrued through any date you choose, and the payment that stops it.
Federal 2026 data and §6654 rules checked against the official publications, last on 2026-09-05 Runs in your browser — nothing you type is sent anywhere, not even when you reload or share the link No sign-up Methodology and data status
- Required annual payment
- $14,400
- Shortfall as of Apr 15, 2027
- $14,400
- Estimated penalty through then
- $661.41
- Required per installment
- $3,600
| Installment | Required by then | Credited by then | Status |
|---|---|---|---|
| 1st · Apr 15, 2026 | $3,600 | $0 | $3,600 short |
| 2nd · Jun 15, 2026 | $7,200 | $0 | $7,200 short |
| 3rd · Sep 15, 2026 | $10,800 | $0 | $10,800 short |
| 4th · Jan 15, 2027 | $14,400 | $0 | $14,400 short |
The charge ran on each installment's shortfall from its due date at the IRS underpayment rate until Apr 15, 2027, the return's due date, when §6654(b)(2) stops it; since then the unpaid tax has drawn interest and the late-payment penalty instead, which are not estimated here; quarters the IRS has not yet announced use the last published rate. The figures above are that scenario, not your position today; they change to today's date once the page loads. Withholding counts evenly across the four dates whenever it is withheld; an estimated payment counts on its date, and one made after a due date is counted at the next one here, which slightly overstates the charge. The figure is an estimate under the regular installment method; Form 2210 is the authority, and its annualized method or a waiver can reduce it.
How the penalty is computed
Section 6654 charges an addition to tax on each installment that was underpaid as of its due date, computed like interest: the shortfall, times the IRS underpayment rate, times the days late divided by 365. The required installment is one quarter of the required annual payment — the smaller of 90% of this year's tax and 100% of last year's (110% when last year's AGI exceeded $150,000, $75,000 married filing separately). The period runs from the due date to the earlier of the day the shortfall is paid and April 15 of the following year (§6654(b)(2)); payments are credited to the oldest unpaid installment first (§6654(b)(3)).
| 2026 quarter | Underpayment rate (§6621) |
|---|---|
| January – March | 7% |
| April – June | 6% |
| July – September | 7% |
| October – December | 7% |
Later quarters are announced about six weeks before they begin; until then the calculator carries the last published rate forward and says so. The mechanics, the day counts and the exceptions are explained in what happens if you miss a quarterly payment.
Two crediting rules that change the answer
Withholding is spread evenly. Federal income tax withheld from wages, a pension or other income is deemed paid in four equal parts on the four due dates, whenever it was actually withheld (§6654(g)(1)). Enter the whole year's expected withholding; a filer with a job who is short can raise withholding late in the year and have it count from April, as described in the withholding guide.
Estimated payments count on their dates. A payment made by a due date belongs to that installment; one made after it belongs, in this calculator, to the next due date. The real rule is more precise — the charge stops on the day of payment — so a payment made a few days late is overstated here by those days. Form 2210 computes it exactly.
What removes the penalty
- Tax after withholding under $1,000 (§6654(e)(1)).
- No tax liability in the prior year, if it was a full twelve-month year and you were a U.S. citizen or resident throughout (§6654(e)(2)).
- A waiver for casualty, disaster or unusual circumstances, or for a filer who retired after 62 or became disabled and had reasonable cause (§6654(e)(3)), requested on Form 2210 Part II.
- The annualized income installment method, when income arrived late in the year — see the annualized method guide.
Reporting
Form 2210 is optional in the ordinary case: leave it off and the IRS computes the penalty from the return and the payment record and sends a bill. File it, with the amount on the estimated tax penalty line of Form 1040, when a waiver or the annualized method applies, or when withholding should be credited on its actual dates. The figure here is a planning estimate under the regular method.