Estimated Tax Payments Calculator
Estimate your quarterly IRS tax payments to stay compliant and avoid underpayment penalties. Useful for freelancers, self-employed individuals, and anyone with income not subject to automatic withholding.
Last updated: September 2026
Formula below · 1 source (IRS) · Updated Sep 2026
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About this calculator
To avoid the IRS underpayment penalty you must pay in, through withholding plus four timely estimated payments, the smaller of two safe-harbor amounts: (a) 90% of this year's tax, or (b) 100% of last year's total tax, or 110% if last year's AGI was over $150,000 ($75,000 married filing separately). This calculator estimates this year's tax with the 2026 federal brackets for your filing status applied to expected income minus your deduction (2026 standard deduction: $16,100 single or married filing separately, $32,200 married filing jointly, $24,150 head of household), plus any other taxes you enter such as self-employment tax. Quarterly Payment = max(0, min(90% × this year's tax, prior-year tax × 100% or 110%) − tax already withheld) ÷ 4. Paying the smaller safe-harbor amount is enough to avoid the penalty even if you still owe a balance in April. Withholding counts as paid evenly through the year, so it reduces every installment. Not modeled: credits, capital-gain rates, the annualized-income method for uneven income, and the $1,000 rule (no penalty if you owe less than $1,000 after withholding). The prior-year safe harbor only applies if last year was a full 12-month tax year and you filed a return; if you owed no tax at all last year, no estimated payments are required. The four installments are due April 15, June 15 and September 15, 2026 and January 15, 2027.
How to use
Assume a single filer with expectedIncome = $90,000, deductions = $16,100, withheldTaxes = $5,000, priorYearTax = $14,000, no other taxes, and prior-year AGI under $150,000. Step 1: Taxable income = $90,000 − $16,100 = $73,900. 2026 tax = 10% × $12,400 + 12% × $38,000 + 22% × $23,500 = $1,240 + $4,560 + $5,170 = $10,970. Step 2: 90% of this year's tax = $9,873. Step 3: Prior-year safe harbor = $14,000 × 100% = $14,000. Step 4: Required = the smaller, $9,873. Step 5: Quarterly payment = ($9,873 − $5,000) ÷ 4 = $1,218.25. Paying $1,218.25 on each due date avoids the penalty; the remaining roughly $1,097 of 2026 tax is due with your return. If you are self-employed, enter your expected self-employment tax in Other Expected Taxes (for $90,000 of net profit it is about $12,717), since it is part of the tax the safe harbor is measured against.
Frequently asked questions
When are quarterly estimated tax payments due to the IRS?
The IRS sets four payment deadlines each year: April 15 for Q1 (January–March income), June 15 for Q2, September 15 for Q3, and January 15 of the following year for Q4. If any deadline falls on a weekend or federal holiday, it shifts to the next business day. Missing these deadlines can trigger an underpayment penalty even if you pay your full balance by Tax Day in April. Setting calendar reminders well in advance helps self-employed individuals and investors stay on schedule.
How does the safe harbor rule help me avoid IRS underpayment penalties?
The safe harbor lets you avoid the underpayment penalty if your withholding plus timely estimated payments reach the smaller of 90% of this year's tax or 100% of last year's total tax (110% if last year's AGI exceeded $150,000, or $75,000 married filing separately). The prior-year test is especially useful when this year's income is hard to predict or rising: you can simply base payments on last year's Form 1040 total tax. Even if you end up owing more at filing time, no penalty applies once the safe-harbor amount was paid on time.
What happens if I underpay my estimated taxes during the year?
If your payments for a quarter fall short of the required installment, the IRS charges an underpayment penalty that works like interest: the federal short-term rate plus 3 percentage points (7% a year for most of 2026; it was 6% in the second quarter), applied to the shortfall for each day it remains unpaid. The penalty is computed per installment, so underpaying early in the year costs more than underpaying in Q4. Form 2210 calculates the exact penalty and lets you use the annualized-income method or claim a waiver for casualty, disaster or other unusual circumstances.