IRS Form 2210 · Section 6654 · 2026
Enter your quarterly payments and prior-year tax to estimate the IRS underpayment penalty under IRC Section 6654. Applies safe harbor rules automatically. No penalty if you qualify.
This calculator estimates your IRS underpayment penalty and interest for missed or short quarterly estimated tax payments in 2025 and 2026, using Form 2210 logic and the current federal short-term rate. The penalty is calculated per quarter at the federal short-term rate plus 3 percentage points (approximately 7% annualized for Q1 2026 and 6% for Q2 2026), compounded daily on the underpaid amount. You can avoid the penalty entirely by meeting either IRC § 6654 safe harbor: pay at least 90% of this year's tax or 100% of last year's tax (110% if prior-year AGI exceeded $150,000).
| Item | Value / Rule |
|---|---|
| Q1 2026 penalty rate | 7% annualized (4% short-term + 3 pts) per Rev. Rul. 2025-22 |
| Q2 2026 penalty rate | 6% annualized (3% short-term + 3 pts) per Rev. Rul. 2026-5 |
| Rate authority | IRC §6621: federal short-term AFR + 3 percentage points |
| Safe Harbor 1 | 90% of current-year tax (22.5% per quarter) |
| Safe Harbor 2 (AGI ≤ $150K) | 100% of prior-year tax (25% per quarter) |
| Safe Harbor 2 (AGI > $150K) | 110% of prior-year tax (27.5% per quarter) |
| $1,000 exception | No penalty if total underpayment under $1,000 after withholding |
| Governing form | IRS Form 2210 (Annualized Method: Schedule AI) |
| Quarterly due dates (2026) | Apr 15 / Jun 15 / Sep 15 / Jan 15, 2027 |
The IRS requires quarterly estimated tax payments on this schedule for tax year 2026:
Note: Q2 covers only two months (April–May) and Q3 covers three months (June–August). This is a quirk of the IRS schedule. See 2026 Tax Deadlines for the full calendar.
The penalty is governed by IRC Section 6654 and computed using IRS Form 2210. The mechanics:
Step 1: Determine required quarterly payment. You must pay the lesser of: (a) 22.5% of current-year expected tax each quarter (90% ÷ 4), or (b) 25% of prior-year total tax each quarter (100% ÷ 4). If prior-year AGI exceeded $150,000, use 27.5% of prior-year tax (110% ÷ 4).
Step 2: Determine underpayment amount per quarter. Underpayment = Required Payment minus Actual Payment (estimated payment + withholding allocated to that quarter).
Step 3: Apply the penalty rate. The penalty rate is the federal short-term interest rate plus 3 percentage points, rounded to the nearest whole percent. For Q1 2026, this rate is 7% (Rev. Rul. 2025-22). For Q2 2026, the rate decreased to 6% (Rev. Rul. 2026-5). The penalty is compounded daily on the underpaid amount from the due date of the quarterly payment to the earlier of: the date you paid enough, or April 15 of the following year (filing deadline).
Simplified formula: Penalty ≈ Underpayment × Rate × (Days Underpaid ÷ 365)
For example: $5,000 underpaid for Q1 2026 from April 15 to October 15 (183 days): $5,000 × 7% × (183/365) ≈ $175.48.
You can receive a year-end refund and still owe an underpayment penalty. The penalty and the refund are two different calculations.
The underpayment penalty is calculated separately for each quarter. If you paid too little in Q1, you owe a penalty on that Q1 shortfall for the days between April 15 and when the payment was made — regardless of what you paid later in the year. A large Q4 withholding or estimated payment does not retroactively reduce Q1–Q3 penalties.
The refund you receive at filing reflects the difference between your total annual tax liability and your total annual payments. The penalty reflects whether each quarterly installment was timely and sufficient. Both can be true simultaneously: enough total annual payments to generate a refund, but quarterly timing that still triggers a penalty.
The IRS provides two safe harbors that, if met, guarantee no underpayment penalty regardless of your actual tax liability:
If your total payments (estimated payments + W-2 withholding) equal at least 90% of your current-year tax liability, no penalty applies. This requires estimating your current-year income accurately, making it harder to use if your income is unpredictable.
If your total payments equal at least 100% of your prior-year total tax, no penalty applies. If your prior-year adjusted gross income (AGI) exceeded $150,000 ($75,000 for married filing separately), the threshold increases to 110% of prior-year tax.
The prior-year safe harbor is preferred by most self-employed workers and freelancers because the target amount is known with certainty. Look at your prior year Form 1040, line 24 (total tax), and divide by 4 to find your equal quarterly payment. This approach fully shields you from any underpayment penalty.
This calculator is not a replacement for Form 2210, which uses the Annualized Income Installment Method and provides the legally binding penalty calculation. For formal penalty disputes or IRS notices, contact LMN Tax Inc for professional assistance.
Most underpayment penalties affect self-employed individuals. For how SE tax is calculated and how to plan quarterly payments, see our Self-Employment Tax Guide.
If your income was not evenly distributed throughout the year — for example, you earned most of your income in Q3 or Q4 — the standard method may over-calculate your penalty. Form 2210's Annualized Income Installment Method (Schedule AI) recalculates required payments based on what you actually earned in each period, potentially eliminating or significantly reducing the penalty.
For example: if you earned nothing in Q1 through Q3 and then received a large contract payment in Q4, your required quarterly payments for Q1–Q3 under the annualized method would be zero because your annualized income for those periods was zero. Under the standard method, you would appear to have underpaid those quarters.
Filing Form 2210 with Schedule AI is voluntary but highly recommended when income is seasonal or back-loaded. The IRS calculates the penalty automatically using the standard method if Form 2210 is not filed. You must file it to claim the annualized method benefit.
Net SE income: $60,000. Prior-year W-2 income tax (Form 1040, Line 24): $4,200. Quarterly payments made: $0. Filing in April 2027.
Four payments of $1,050 on the quarterly due dates would have eliminated the entire $178 penalty. The prior-year safe harbor is the most reliable method for first-year self-employed workers because the target is fixed regardless of current-year income. If Maya's prior-year AGI exceeded $150,000, the 110% threshold applies: $4,620 ÷ 4 = $1,155 per quarter. These day counts are approximate. The actual per-day count may vary by one to two days depending on weekends and federal holidays shifting due dates. This example uses 6% for the Q2 through Q4 2026 penalty periods; the IRS announces quarterly rates separately and Q3 and Q4 rates may differ. See IRS.gov/payments/quarterly-interest-rates for current rates.
At LMN Tax Inc., the estimated tax penalty is the most overlooked cost in a client's first year of self-employment. Clients who earned $60,000 in freelance income and paid nothing until April routinely owe a penalty in the $200–$400 range. The fix is straightforward: four quarterly payments using the prior-year safe harbor method. Most first-year self-employed clients who come to us in March could have avoided the penalty entirely with one calculation in April of the prior year.
The prior-year safe harbor is the more reliable shield. We calculate the client's prior-year Form 1040 Line 24 total tax, divide by four, and set a calendar reminder for each quarterly due date. The only variable is whether prior-year AGI exceeded $150,000, which triggers the 110% threshold. This method requires zero estimation of current-year income and fully eliminates the penalty regardless of what the client earns in the current year.
When a client comes in with a penalty notice after an uneven income year, our first step is always Form 2210 Schedule AI. Freelancers who earned most of their income in Q3 or Q4 frequently owe nothing after the annualized method is applied. The IRS does not automatically apply the annualized method — you have to file Form 2210 to claim it. If a penalty was assessed without Schedule AI and income was back-loaded, filing an amended Form 2210 can eliminate or substantially reduce the assessed amount.
If the calculator shows a penalty: first check whether your income was unevenly distributed. If yes, file Form 2210 with Schedule AI before paying the penalty. For many freelancers with Q3/Q4-heavy income, the annualized method reduces the penalty to zero without any additional payment.
If the penalty is valid and you have not received a formal notice yet: the IRS will calculate it automatically when you file Form 1040. You do not need to pay it separately in advance. It will appear on your return as an addition to your tax due.
If the calculator shows no penalty: verify that your inputs match your actual Form 1040 Line 24 prior-year total tax and your actual payment records. Even a small discrepancy in prior-year tax can shift the result. The safe harbor threshold is precise: any shortfall, even by $1, technically subjects you to the penalty on that quarter's underpaid amount.
Going forward: set up four equal quarterly payments using the prior-year safe harbor method. This completely eliminates penalty risk regardless of current-year income fluctuations. Use the 1099 Tax Calculator to estimate this year's total tax, then divide by four to know your target amount for each quarter.
If you already owe a balance you cannot pay in full, the IRS offers payment plans that allow up to 72 months to resolve the debt. The IRS Payment Plan Calculator estimates your monthly payment, setup fee, and total interest cost so you can compare short-term and long-term plan options before applying.
If your underpayment includes federal tax on unemployment benefits, use the Unemployment Tax Calculator to confirm the exact amount owed on your 1099-G income before re-running this penalty estimate with corrected numbers.
Graduate students and fellowship recipients with taxable stipend or scholarship income often owe estimated tax but have no withholding. Use the Scholarship Tax Calculator to determine your taxable scholarship amount, then re-run this penalty estimate to see if quarterly payments were required.
Not sure you need to file at all? If your income is near the standard deduction level, use the Do I Need to File Taxes? Calculator to confirm your filing requirement before running this penalty estimate.