ABOUT
What's under the hood
Every number on this site comes from a documented calculation, not a black box. Here's exactly what we model, what we simplify, and where to go for precision.
Federal income tax
We apply the full 2026 progressive bracket schedule (10% to 37%) published in IRS Revenue Procedure 2025-32, along with the 2026 standard deduction for single and married-filing-jointly filers. We don't model itemized deductions, above-the-line adjustments beyond 401(k)/section 125, or credit phase-outs beyond a flat child tax credit on the refund estimator.
FICA (Social Security & Medicare)
Social Security is calculated at 6.2% up to the 2026 wage base of $184,500. Medicare is 1.45% on all wages, plus the additional 0.9% Medicare surtax above $200,000 (single) or $250,000 (married), per SSA and IRS guidance for 2026.
State tax
We model state tax two different ways, and we tell you which one applies:
Bracket-based (California, New York)
We use each state's actual published bracket schedule and standard deduction. This is the most accurate approach we offer, though it still excludes things like California SDI or New York City local tax.
Flat-rate estimate (everywhere else)
For the remaining 48 states and DC, we apply a single representative effective rate rather than each state's full bracket structure. It's a useful ballpark, not a filing-grade number — states with true progressive brackets will differ, sometimes by more than a point.
What we intentionally leave out
Local and city income tax (outside the New York State/NYC note), self-employment tax, itemized deductions, alternative minimum tax, credit phase-outs at higher incomes, and state-specific payroll items like California SDI or Washington's Paid Family & Medical Leave premium.
Sources
- IRS — Revenue Procedure 2025-32, 2026 inflation adjustments
- Social Security Administration — 2026 wage base and FICA rates
- State revenue department bracket schedules (California FTB, New York State Department of Taxation and Finance)
This site is built for quick, directional estimates — not for filing your return. For anything with real dollars on the line, verify against your latest pay stub or a licensed tax professional.