How this is calculated
- Self-employment (SE) tax. Your net SE income is multiplied by
0.9235to get net earnings from self-employment (this removes the employer-half equivalent). We then apply15.3%(12.4% Social Security + 2.9% Medicare) to net earnings up to the 2026 Social Security wage base of$184,500, and2.9%Medicare on any net earnings above it. - Federal income tax. Taxable income
= net SE income − standard deduction − ½ of SE tax. The 2026 standard deduction is$16,100 single / $32,200 MFJ, and half your SE tax is an above-the-line deduction. We apply the 2026 marginal brackets (10/12/22/24/32/35/37%) from IRS Revenue Procedure 2025-32:tax = Σ (bracket rate × income in that bracket). - Total 2026 tax
= income tax + SE tax. - Safe-harbor required annual payment. To avoid an underpayment penalty you
pay the lesser of (a)
90% × this year's total tax, or (b)100% × prior-year tax— which rises to110%if your prior-year AGI was over$150,000. The badge and note above tell you which one is binding. - Each quarterly payment
= (required annual payment − expected withholding) ÷ 4, split evenly across the four 2026 installments: Apr 15, 2026 · Jun 16, 2026 · Sep 15, 2026 · Jan 15, 2027. If withholding already meets the required amount, the quarterly payment is $0.
What this doesn't model: state estimated taxes, the Qualified Business Income (QBI) deduction, itemized deductions, tax credits (child tax credit, EITC, education), the 0.9% Additional Medicare Tax at high incomes, W-2 wages alongside self-employment, the annualized-income method for uneven earnings, or non-calendar fiscal years. It's a solid first estimate of your 1040-ES payments — not a filed return. Data as of 2026 (tax year 2026).
Conceptual sources (not linked, referenced by name): the Internal Revenue Service (IRS Form 1040-ES and Revenue Procedure 2025-32) and the Social Security Administration (SSA) 2026 wage base.
Frequently asked questions
Who has to pay quarterly estimated taxes?
Generally, if you expect to owe at least $1,000 in tax for the year after subtracting withholding and refundable credits, the IRS wants you to pay estimated taxes in four installments. This mostly affects self-employed people, freelancers, gig and 1099 workers, landlords, and investors — anyone whose income is not covered by paycheck withholding. If a spouse's W-2 withholding already covers your combined tax, you may owe little or nothing extra.
What is the safe harbor rule for estimated taxes?
You avoid an underpayment penalty if your total payments (withholding plus estimates) reach the smaller of: 90% of the tax you owe this year, or 100% of the tax shown on last year's return. That prior-year figure rises to 110% if your prior-year adjusted gross income (AGI) was over $150,000 ($75,000 if married filing separately). Because it is the lesser of the two, a low prior-year tax bill can sharply reduce what you must prepay this year.
What are the 2026 estimated tax due dates?
For tax year 2026 the four Form 1040-ES installments are due April 15, 2026 (Q1), June 16, 2026 (Q2), September 15, 2026 (Q3), and January 15, 2027 (Q4). If a due date falls on a weekend or holiday it shifts to the next business day. You can skip the January payment if you file your return and pay the balance in full by February 1, 2027.
Does this calculator send my income anywhere?
No. Everything runs locally in your browser; nothing you type is transmitted to a server. The copy-shareable-link button encodes your inputs into the URL itself, so only people you share that link with can see them.
Estimates only — not tax advice; consult a tax professional. Safe-harbor rules have exceptions (farmers and fishermen, higher-income filers, the annualized-income method for uneven earnings, and special first-year rules), and this tool does not model state estimated taxes, credits, the QBI deduction, or the Additional Medicare Tax. No liability is accepted for decisions made from these results.