Quarterly Estimated Taxes Calculator (2026 SE Tax + Income Tax)

Self-employed workers owe federal tax in four installments during the year rather than through employer withholding. The quarterly payment is composed of two mostly-separate taxes. Self-employment tax (Schedule SE) covers Social Security and Medicare, the parts an employer normally withholds and matches for a W-2 employee. Federal income tax is the bracketed tax on taxable income after the standard deduction, the deduction for half of the SE tax, and the Qualified Business Income deduction if it applies. Both pieces combine into a single annual federal tax bill, which this tool divides by four to give you the amount to send IRS on each estimated-tax due date.

Enter your projected net self-employment income for the year (Schedule C line 31). Pick a filing status. Optionally enter your W-2 wages from a second source and toggle whether your SE income qualifies for the QBI deduction. The tool computes SE tax using the Form 1040-ES 2026 SE Tax Worksheet (net × 0.9235 × 12.4% on amounts up to the $184,500 Social Security wage base plus × 2.9% Medicare on all net earnings), applies the Additional Medicare Tax at 0.9% on combined wages plus SE earnings over the filing-status threshold, subtracts half the SE tax from gross income, subtracts the standard deduction, applies the IRC 199A QBI deduction if you indicated eligibility, and runs the remainder through the 2026 Tax Rate Schedules from Form 1040-ES.

This is a ballpark. For a real quarterly number, use IRS Form 1040-ES and its worksheet, or your tax software. State estimated tax is not included. Safe-harbor rules (IRC 6654), self-employed retirement contributions, self-employed health insurance deduction, and QBI phase-outs for specified service businesses at high income are not modeled. See the methodology page for the data sources behind the 2026 tax figures used here.

Schedule SE computation (Form 1040-ES 2026 SE Tax Worksheet): multiply net SE income by 0.9235 to get "SE earnings" (the 0.9235 factor reverses the employer-equivalent half of FICA that is deductible before computing SE tax). Apply 12.4% Social Security on the smaller of SE earnings or the remaining 2026 wage base of $184,500 (after subtracting any W-2 wages already subject to SS). Apply 2.9% Medicare on all SE earnings. Per IRC 164(f), half of the resulting SE tax is deductible from gross income to compute AGI.

Additional Medicare Tax (IRC 1401(b)(2)): an extra 0.9% applies to combined (wages + SE earnings) in excess of the filing-status threshold. Thresholds are not indexed to inflation and have been constant since the Affordable Care Act: $200,000 for single and head of household, $250,000 for married filing jointly, $125,000 for married filing separately.

Federal income tax: subtract the 2026 standard deduction for the filing status from AGI. Subtract the IRC 199A QBI deduction if applicable. The tool computes this as the lesser of 20% of qualified business income or 20% of taxable income before the QBI deduction, assuming non-SSTB and below-threshold income (the W-2 wage and UBIA limits are out of scope). Run the remainder through the 2026 Tax Rate Schedules from Form 1040-ES page 9 (Schedule X for Single, Y-1 for MFJ, Y-2 for MFS, Z for Head of Household).

Total federal tax equals SE tax plus Additional Medicare plus income tax. Divide by four to get each quarterly installment per IRS Form 1040-ES. Safe-harbor rules under IRC 6654 let you avoid underpayment penalties by paying 90% of current-year tax OR 100% of prior-year tax (110% if prior-year AGI was over $150,000); this tool does not check safe harbor and computes the current-year estimate only.

Use this at the start of a freelance year to ballpark quarterly payments, when onboarding a new ongoing client and projected income changes materially, or when a CPA gives you a quarterly figure and you want to sanity-check it. For the first year of self-employment, safe-harbor rules (prior year × 100% or 110%) can reduce the required quarterly payment; the tool does not model that path because it does not take prior-year tax as input. The hourly to salary tool pairs with this when converting a contractor rate into after-tax income.