Methodology & Data Sources

What every calculation includes

• Federal income tax using the seven 2026 brackets from IRS Rev. Proc. 2025-32, applied to gross pay minus the standard deduction ($16,100 single / $32,200 married filing jointly).
• FICA payroll taxes: Social Security at 6.2% of wages up to the 2026 cap of $184,500, Medicare at 1.45% of all wages, and the 0.9% Additional Medicare Tax on wages above $200,000 (single) / $250,000 (married).
• State income tax for all 50 states and DC using 2026 rates, brackets, standard deductions, exemptions, and flat-amount credits as compiled by the Tax Foundation (as of January 1, 2026) and cross-checked against state revenue departments.
• Mandatory state employee payroll taxes where significant: California SDI (1.3%, uncapped), Massachusetts PFML (0.46%), and Washington's WA Cares (0.58%).
• Optional traditional 401(k) deferrals, which reduce federal and (except in Pennsylvania) state taxable income but not FICA wages, capped at the $24,500 limit.

Standard assumptions

• You take the standard deduction (about 90% of filers do post-2018), have no dependents, and claim no itemized deductions or credits beyond what's listed above.
• Wage income only: no self-employment, capital gains, bonuses taxed at supplemental rates, or multiple jobs.
• Full-year residency in the selected state. Hourly conversions assume 40 hours/week, 52 weeks/year (2,080 hours) unless you change them.
• Married figures assume one earner; two-earner households can differ because FICA and some state brackets apply per person.

Known limitations (read this)

• Local income taxes are excluded everywhere. This matters most in Maryland (county taxes of 2.25%–3.2%), New York City (3.078%–3.876%), Ohio and Pennsylvania municipalities (~1%–3%), and a few others. Every affected state page carries a warning.
• A few niche state provisions are approximated: federal-tax deductibility (Alabama, Missouri, Oregon and others), Connecticut's benefit recapture, Arkansas's low-income tables, and high-income phase-outs of deductions in a few states. Where we approximate, the state page says so and in which direction the error runs.
• Employer benefits (health premiums, HSA/FSA, commuter) and post-tax deductions aren't modeled; they're specific to your employer.
• These are educational estimates, not tax advice. Your W-4, employer payroll system, and year-end return determine actual amounts.

How we keep data current

• Federal parameters update each November when the IRS publishes inflation adjustments; state parameters update each January–February when states finalize rates and the Tax Foundation publishes its annual compilation.
• Every page footer shows the verification date (currently June 2026). Mid-year state changes (like South Carolina's scheduled July 2026 reversion) are noted on the relevant state page.
• Spot a stale number? Email us via the contact page. Corrections ship within days.

Verify our math

Pick any salary and run it through the calculator, then check the federal piece by hand against the 2026 bracket table. The engine is deterministic: same inputs, same answer, no black-box adjustments.