Estimated Tax Penalty Calculator (Form 2210)
Find out if you owe an IRS underpayment penalty for tax year 2025 or 2026. Check safe harbor, compute quarterly underpayments, and see the interest at the current 6% IRS underpayment rate.
Total tax after credits but before withholding.
W-2 + 1099 withholding (treated as paid evenly).
Used for 100%/110% safe harbor.
If > $150k, safe harbor rises to 110% of prior year tax.
Estimated Payments Made
| Period | Due Date | Required Cum. | Paid Cum. | Underpaid | Days | Penalty |
|---|---|---|---|---|---|---|
| Q1 | 2026-04-15 | $5,000 | $2,500 | $2,500 | 366 | $170.21 |
| Q2 | 2026-06-15 | $10,000 | $5,000 | $5,000 | 305 | $290.27 |
| Q3 | 2026-09-15 | $15,000 | $7,500 | $7,500 | 213 | $306.37 |
| Q4 | 2027-01-15 | $20,000 | $10,000 | $10,000 | 91 | $174.52 |
| Total Penalty | $941.37 | |||||
How the penalty works
The IRS expects income tax to be paid as you earn it. If your withholding plus timely estimated payments falls short of the required installment for any quarter, a non-deductible interest charge accrues on the underpaid balance until the earlier of the date you catch up or April 15 of the following year.
Two simple tests let most taxpayers avoid the penalty entirely:
- De minimis — balance owed after withholding is under $1,000.
- Safe harbor — you paid at least 90% of current year tax or 100% of prior year tax (110% if prior AGI > $150,000).
When neither test is met, Form 2210 breaks the year into four periods. Each period has a required cumulative payment (25% / 50% / 75% / 100% of the required annual amount). Any cumulative shortfall accrues interest at the quarterly IRS underpayment rate until paid.
IRS underpayment interest rate by quarter
The penalty is interest on each quarter's shortfall at the IRS underpayment rate (federal short-term rate + 3 points), which can change every quarter. These are the individual rates this calculator applies:
| Quarter | Underpayment rate |
|---|---|
| Q1 2025 (Jan–Mar) | 8% |
| Q2 2025 (Apr–Jun) | 7% |
| Q3 2025 (Jul–Sep) | 7% |
| Q4 2025 (Oct–Dec) | 7% |
| Q1 2026 (Jan–Mar) | 7% |
| Q2 2026 (Apr–Jun) | 6% |
| Q3 2026 (Jul–Sep) | 7% |
Rates source: IRS quarterly interest rates (federal short-term rate + 3%). Interest compounds daily.
Required installment schedule (regular method)
Form 2210's regular method splits your required annual payment into four equal installments. By each due date you must have paid the cumulative percentage below, or interest accrues on the shortfall:
| Installment | Due date | This installment | Cumulative |
|---|---|---|---|
| Q1 | Apr 15 | 25% | 25% |
| Q2 | Jun 15 | 25% | 50% |
| Q3 | Sep 15 | 25% | 75% |
| Q4 | Jan 15 | 25% | 100% |
The "required annual payment" is the safe-harbor amount — the smaller of 90% of current-year tax or 100%/110% of prior-year tax. The annualized income method (Schedule AI) replaces these equal installments with 22.5% / 45% / 67.5% / 90% cumulative targets when income is uneven.
Worked example
Freelancer, 2026 tax year, no withholding
Maria expects $12,000 of total 2026 tax and has no W-2 withholding. Her safe harbor (90% of current-year tax) is $10,800, so her required installment is $2,700 per quarter ($10,800 ÷ 4).
She pays nothing during the year. Her Q1 installment of $2,700 is outstanding from April 15, 2026 until she files on April 15, 2027 — roughly a full year. At the 6%–7% IRS underpayment rate, the interest on that one installment is about $2,700 × 7% ≈ $189. Each later installment accrues interest for a shorter window, so her total Form 2210 penalty lands near $450–$500.
Had her prior-year tax been only $6,000, the 100% prior-year safe harbor ($6,000) would have been the smaller target — paying $1,500/quarter would have avoided the penalty entirely. Enter your own numbers above for an exact figure.
Frequently asked questions
When do I owe a Form 2210 underpayment penalty?
You generally owe a penalty if your total withholding and timely estimated payments fall short of the smaller of (a) 90% of your current year's tax or (b) 100% of last year's tax (110% if your prior AGI exceeded $150,000). There is no penalty if the balance you owe after withholding is under $1,000.
What is the IRS underpayment interest rate for 2025 and 2026?
The IRS underpayment rate is the federal short-term rate plus 3 percentage points, set each quarter by Revenue Ruling. It was 8% for Q1 2025, 7% for Q2–Q4 2025 and Q1 2026, dropped to 6% for Q2 2026 (Apr–Jun), and is 7% again for Q3 2026 (Jul–Sep). See the quarter-by-quarter table above. Interest is compounded daily.
Does withholding count differently from estimated payments?
Yes. Form 2210 treats withholding as paid evenly across the four installment due dates (Apr 15, Jun 15, Sep 15, Jan 15) by default, even if it was actually withheld only late in the year. Estimated payments only count for the quarter in which they were actually made.
Do I need to file Form 2210 with my return?
For most taxpayers, no — the IRS will calculate the penalty and bill you if one is owed. You must file Form 2210 when you are requesting a waiver, using the annualized income installment method (Schedule AI), treating withholding as paid when it was actually withheld, or in certain joint-to-single filing situations.
Can I reduce the penalty if my income was uneven?
Yes. If your income arrived late in the year (e.g., a year-end capital gain or contractor bonus), you can file Form 2210 Schedule AI to annualize income and shift the required installments later. This calculator uses the simpler regular method; use Schedule AI manually if your income is heavily back-loaded.
Sources
Related insights
Use these guides for rule explanations, planning context, and follow-up questions beyond the calculator result.
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