TaxWrenMethodology and sources
Last updated
TaxWren estimates US taxes from official figures published by the IRS, the Social Security Administration and state revenue departments. Calculations run in your browser with the same code that produces the numbers shown on every page. We do not store anything you type.
Federal figures for 2026
| Item | Single | Married filing jointly | Head of household |
|---|---|---|---|
| Standard deduction | $16,100 | $32,200 | $24,150 |
| 37% bracket starts | $640,600 | $768,700 | $640,600 |
| QBI phase-out starts | $201,750 | $403,500 | $201,750 |
| Additional Medicare threshold | $200,000 | $250,000 | $200,000 |
Social Security wage base: $184,500. Child tax credit: $2,200 per child, up to $1,700 refundable.
How each calculation works
- Self-employment tax: 12.4% Social Security and 2.9% Medicare on 92.35% of net profit. W-2 wages use up the Social Security wage base first. No tax applies below $400 of net earnings.
- Adjusted gross income: wages and net profit, minus half of self-employment tax, SEP IRA or Solo 401(k) contributions and self-employed health insurance.
- QBI deduction (Section 199A): 20% of qualified business income, limited to 20% of taxable income before the deduction. We assume a sole proprietor with no employees or business property, so above the threshold the deduction phases out linearly to zero. Since 2026 a minimum deduction of $400 applies with at least $1,000 of QBI.
- Income tax: the 2026 brackets applied to taxable income, minus the child tax credit (phased out by $50 per $1,000 of AGI above $200,000, or $400,000 married filing jointly).
- State income tax: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, Wyoming do not tax wages or self-employment income. Other states are added one by one after their rules are checked against the state's own publications; until then the calculator says so instead of guessing.
What we do not cover
- Itemized deductions, the alternative minimum tax, capital gains and the earned income tax credit.
- The 2025 law deductions for tips, overtime, seniors and car loan interest.
- Municipal income taxes in Ohio and Pennsylvania.
Sources
- IRS Rev. Proc. 2025-32 (2026 inflation adjustments)
- SSA: Contribution and benefit base
- IRS Topic 554: Self-employment tax
- IRS Topic 560: Additional Medicare tax
Data last verified 2026-10-10. Read our editorial policy for how figures are updated.