Estimated Tax Penalty Calculator 2026
If your 2026 estimated tax payments were late or too small, the IRS adds an underpayment penalty. Enter your tax, withholding and payment dates to estimate it the way Form 2210 does.
Your numbers
List the estimated payments you made for 2026 (or plan to make), with the date each one was paid. Add a 2025 refund applied to 2026 as a payment dated Apr 15, 2026.
Enter yearly amounts in US dollars. Results update as you type and never leave your browser.
Last reviewed: October 30, 2026.
How we calculate it
We follow the regular method of IRS Form 2210 and its Penalty Worksheet:
- $1,000 test. If your 2026 tax minus withholding is under $1,000, there is no penalty.
- Required annual payment = the lower of 90% of your 2026 tax or 100% of your 2025 tax (110% if your 2025 AGI was over $150,000, or $75,000 married filing separately). The 2025 option only counts if your 2025 return covered 12 months.
- Installments. 25% of that amount is due by each date: April 15, June 15 and September 15, 2026, and January 15, 2027.
- Withholding is treated as paid in four equal parts on the due dates. The Form 2210 instructions let you elect to use the actual dates your withholding was paid instead; this calculator assumes even spreading. Estimated payments count on the date you made them.
- Order of payments. Each payment goes first to the earliest installment that is still short, even if you meant it for a later quarter.
- Penalty on each short amount = amount × rate × days late ÷ 365, from the due date to the date it was paid or April 15, 2027, whichever is earlier. It is simple interest: the daily compounding used for other IRS interest does not apply to this penalty (26 U.S.C. § 6622(b)).
| Rate period | Annual rate |
|---|---|
| Apr 16 – Jun 30, 2026 | 6% |
| Jul 1 – Sep 30, 2026 | 7% |
| Oct 1 – Dec 31, 2026 | 7% |
| Jan 1 – Apr 15, 2027 | Not announced as of Oct 30, 2026. We assume 7% (the Q4 2026 rate); you can change it. |
If you filed your 2026 return and paid all the tax by February 1, 2027 (January 31 is a Sunday), the January 15 installment has no penalty; set that option to Yes and enter the payment with its date. Not covered: the annualized income installment method (Schedule AI), penalty waivers, special rules for farmers and fishermen, and state penalties.
Worked example
Single filer. 2026 tax $12,000, no withholding. 2025 tax $8,000 with AGI $60,000, so the 100% rule applies. Required annual payment: the lower of $10,800 (90% × $12,000) or $8,000, so $8,000, or $2,000 per due date. Payments: $2,000 on Jun 15, 2026, $3,000 on Oct 15, 2026 and $2,000 on Jan 15, 2027.
| Short amount | Days and rate | Penalty |
|---|---|---|
| $2,000 due Apr 15, paid Jun 15 | 61 at 6% | $20.05 |
| $2,000 due Jun 15, paid Oct 15 | 15 at 6% + 92 at 7% + 15 at 7% | $4.93 + $35.29 + $5.75 = $45.97 |
| $1,000 due Sep 15, paid Oct 15 | 15 + 15 at 7% | $2.88 + $2.88 = $5.76 |
| $1,000 due Sep 15, paid Jan 15 | 15 + 92 at 7% + 15 at 7%* | $2.88 + $17.64 + $2.88 = $23.40 |
| $1,000 due Jan 15, unpaid on Apr 15 | 90 at 7%* | $17.26 |
Total estimated penalty: $112.44. Each line is amount × rate × days ÷ 365, rounded to the cent. *$20.14 of it uses the assumed 7% rate for 2027, which the IRS has not announced yet.
Related
- 1099 quarterly estimated tax calculator: what to pay each quarter
- Self-employment tax calculator: the SE tax part of your 2026 total tax
- Guide: the January 15, 2027 estimated tax payment
FAQ
How is the estimated tax penalty calculated?
For each installment you underpaid, the IRS charges interest at its underpayment rate from the due date until you pay it or until April 15, 2027, whichever comes first. Form 2210 figures it as amount × rate × days ÷ 365.
How can I avoid the underpayment penalty for 2026?
Pay at least the lower of 90% of your 2026 tax or 100% of your 2025 tax (110% if your 2025 AGI was over $150,000, or $75,000 married filing separately), in four equal parts by each due date. There is also no penalty if you owe less than $1,000 after withholding.
Is the estimated tax penalty compounded daily?
No. Most IRS interest compounds daily, but 26 U.S.C. § 6622(b) excludes the estimated tax penalty, so Form 2210 uses simple interest at the quarterly rate.
What interest rate applies from January to April 2027?
The IRS had not announced the January–March 2027 rate as of October 30, 2026. That rate also covers April 1–15, 2027. We assume 7% (the Q4 2026 rate) and let you change it.
Does a payment for Q3 count toward Q3?
Not if an earlier installment is still short. The IRS applies each payment to the earliest underpaid installment first, even if you designated it for a later quarter.
Sources
- IRS: Underpayment of estimated tax by individuals penalty
- IRS Tax Topic 306: Penalty for underpayment of estimated tax
- IRS: Instructions for Form 2210 (regular method and Penalty Worksheet)
- IRS: Quarterly interest rates (2026: 7%, 6%, 7%, 7%)
- IRS Rev. Rul. 2025-22 (Q1 2026 rates)
- IRS IR-2026-98: rates for the fourth quarter of 2026
- IRS Form 1040-ES (2026): due dates and safe harbor
- 26 U.S.C. § 6654 (estimated tax penalty)
- 26 U.S.C. § 6622(b) (no daily compounding for § 6654)
Last reviewed October 30, 2026 by the Self Employed Math editorial team against the sources above.