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Quarterly estimated tax calculator

2027 projection using 2026 assumptions. Estimates federal income tax plus self-employment tax for a single filer with one sole-proprietor business, then splits the total into four payments.

Scope: the simple case only

  • Single filer, one Schedule C business, standard deduction, no W-2 wages.
  • Not included: state tax, capital gains/qualified dividends, Additional Medicare Tax, AMT, other filing statuses, net losses, specified-service and W-2 wage limits on QBI above $201,750.
  • Assumes QBI equals profit minus half of SE tax minus any business-related adjustments you enter (e.g. SEP or SE health insurance).
  • Not tax advice. An educational estimate only. Confirm with IRS Form 1040-ES or a tax professional.

Estimated per-quarter payment

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    Not tax advice. 2027 projection using 2026 IRS figures; the IRS publishes 2027 figures later.

    How this estimate works

    1. Self-employment tax = 15.3% of 92.35% of net profit (12.4% Social Security up to the $184,500 wage base, plus 2.9% Medicare). Source: IRS, Self-employment tax; SSA contribution base.
    2. AGI = profit + other income − half of SE tax − your adjustments.
    3. Taxable income before QBI = AGI − $16,100 standard deduction.
    4. QBI deduction = the lesser of 20% of QBI or 20% of taxable income; then the $400 minimum (if QBI is at least $1,000) is applied after that limit.
    5. Income tax uses the 2026 single brackets, minus credits. Total ÷ 4 = quarterly payment.

    2026 figures: IRS newsroom and Rev. Proc. 2025-32. Last checked 2026-10-13.

    FAQ

    What figures does this calculator use?

    It is a 2027 projection using 2026 IRS assumptions: the 2026 single standard deduction ($16,100), 2026 single tax brackets, the 2026 Social Security wage base ($184,500) and the 2026 QBI threshold ($201,750). The IRS has not yet published 2027 figures.

    Who is this calculator for?

    A single filer with one sole-proprietor business, the standard deduction, no W-2 wages and only ordinary income. Other situations need a fuller calculation.

    How is the quarterly payment calculated?

    The calculator divides the estimated total federal tax (income tax plus self-employment tax) by four. You may owe less if you use a safe-harbor amount based on last year's tax.

    Is this tax advice?

    No. It is an educational estimate. Confirm with IRS Form 1040-ES or a tax professional.

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