Free Quarterly Tax Calculator 2026

What Are Quarterly Estimated Taxes?

Quarterly estimated taxes are advance federal income tax payments that self-employed individuals, freelancers, gig workers, and small business owners make four times per year to avoid an underpayment penalty at filing time. The IRS pay-as-you-go system requires that taxes be paid throughout the year, not in a single lump sum at filing — and because 1099 contractors have no employer withholding, the responsibility falls on the individual to estimate and remit each quarter.

You must make quarterly payments if you expect to owe 1,000 dollars or more in federal tax for the year after subtracting any withholding and refundable credits. The safe harbor rule says you can avoid the underpayment penalty if you pay either 90 percent of the current year tax liability, or 100 percent of last year tax (110 percent if your prior year AGI exceeded 150,000 dollars). Missing payments triggers an underpayment penalty calculated daily at the federal short-term rate plus 3 percent.

How to Calculate Quarterly Taxes

The four-step process to estimate each quarter accurately:

1. Project your annual self-employment income. Use the most recent three months of revenue as a base, adjusted for seasonal patterns. Subtract estimated annual business expenses (mileage, home office, supplies, professional services, equipment depreciation) to arrive at projected net self-employment income.
2. Calculate annual tax liability. Self-employment tax is 15.3 percent on 92.35 percent of net SE income (up to the 2026 Social Security wage base of 168,600 dollars). Federal income tax sits on top, calculated using the progressive brackets based on filing status and total household income (which includes a spouse W-2 if married filing jointly).
3. Divide by four. Take the combined annual liability, divide by four, and that is your default quarterly payment. The 2026 due dates are April 15 (Q1 income earned January through March), June 15 (Q2 April through May), September 15 (Q3 June through August), and January 15, 2027 (Q4 September through December).
4. Adjust each quarter for actual results. If Q1 income came in 20 percent below projection, reduce the Q2 through Q4 estimates accordingly. If a large contract closed mid-year that doubled the expected income, increase the remaining quarters or expect a balance due at filing. The IRS Form 1040-ES worksheet walks through the calculation, and the safe harbor rule provides a fallback target if you cannot project income accurately.

Pay each quarter through IRS Direct Pay (irs.gov, free, debits your bank account), EFTPS (Electronic Federal Tax Payment System, free, requires advance enrollment), or by mailing a check with Form 1040-ES voucher. State estimated tax payments are typically due on the same dates and require a separate payment to the state tax agency.