The math behind this calculator (click to expand)
Federal income tax uses progressive brackets that stack: each dollar of taxable income is taxed at the bracket it falls into, not your highest bracket. The formula is the sum across brackets of (min(taxable, bracket.max) - bracket.min) * bracket.rate when taxable > bracket.min.
FICA stacks two flat rates: 6.2% Social Security on wages up to the wage base ($176,100 in 2025, $180,000 estimated for 2026 per SSA), plus 1.45% Medicare on all wages, plus a 0.9% Additional Medicare surtax on wages above $200,000 single or $250,000 married. Pre-tax 401(k) reduces taxable income for federal and state income tax but not FICA. State tax follows the state's bracket structure, a flat rate, or zero. Local tax (NYC, Philadelphia, Ohio cities, Maryland counties) adds on top of state tax with its own rules.
Implementation by Michael.
Your Paycheck Has Five Tax Layers - Here's How Each One Works
On an $85,000 salary filing single in Georgia, your biweekly paycheck drops from $3,269 gross to roughly $2,382 net - a 27% reduction. But that 27% isn't one tax. It's five separate calculations stacked on top of each other, each with its own rules. The bracket visualization above shows exactly which dollars hit which rate. Here's what's happening at each layer.
Layer 1: FICA - The Tax That Hits First and Hardest
Before brackets enter the picture, FICA takes 7.65% of every dollar: 6.2% for Social Security (capped at $176,100 in 2025) and 1.45% for Medicare (no cap). On $85,000, that's $6,502/year - $250 per biweekly paycheck. FICA is calculated on gross wages, not taxable income, so pre-tax 401(k) contributions don't reduce it. Earners above $200,000 pay an additional 0.9% Medicare surtax on wages above that threshold.
The Social Security cap creates an interesting effect for higher earners: on a $250,000 salary, SS withholding stops around paycheck #18 (late September), boosting net pay by ~$375/check for the rest of the year.
Layer 2: Federal Tax - Progressive Brackets, Not a Flat Rate
Federal income tax is progressive - different slices of income are taxed at increasing rates. On $85,000 single, subtract the $15,000 standard deduction to get $70,000 taxable. That $70,000 spans three brackets: 10% on the first $11,925, 12% on the next $36,550, and 22% on the remaining $21,525. Total federal tax: ~$10,314 (12.1% effective rate). The bracket viz above shows the 22% bar partially filled - that's your top bracket, and only $21,525 of your income actually pays that rate.
Layer 3: State Tax - Where Geography Costs Real Money
Nine states charge zero income tax. The other 41 (plus DC) range from North Dakota's 1.95% flat rate to California's 13.3% top bracket. On $85,000 single, state tax ranges from $0 in Texas to ~$4,669 in Georgia (5.49% flat) to ~$3,475 in California (progressive - lower than Georgia at this income because CA's steep rates don't bite until ~$68K). Drag the salary slider to $200,000 and watch California overtake Georgia as the effective rate climbs.
Layer 4: Local Tax - The Hidden Layer Most Calculators Miss
About a dozen states allow cities or counties to levy their own income taxes. New York City adds 3.08-3.88% on top of New York State's already-steep rates. Philadelphia charges 3.75% - making PA's flat 3.07% state rate much less flat in practice. Ohio cities like Columbus, Cleveland, and Dayton all charge 2.5%. Maryland counties uniformly add 2.25-3.2%. Portland-area workers face both a Metro SHS tax (1% above $125K) and Multnomah County PFA tax (1.5% above $125K). For an $85,000 earner in NYC, local tax adds ~$3,156/year - more than many states charge in total.
Layer 5: Pre-Tax Deductions - Your Tax Shield
Pre-tax 401(k) contributions reduce taxable income for federal and state taxes (not FICA). At $85,000 in Georgia with a 22% federal + 5.49% state = 27.49% combined marginal rate, every $100 to a 401(k) saves $27.49 in taxes. Contributing $500 per biweekly paycheck ($13,000/year) drops federal tax by ~$2,860 and state tax by ~$714 - total tax savings of $3,574 on a $13,000 contribution. Your paycheck drops by $363, not $500. The bracket visualization shifts visibly when you add deductions - watch the top federal bracket bar shrink.
Withholding vs. Actual Liability
Paycheck withholding is an estimate - it assumes this paycheck is your only income, uses the standard deduction, and spreads annual tax evenly across periods. If you have a side gig, investment income, significant itemized deductions, or child tax credits, your actual liability will differ. The gap shows up as a refund or balance due when you file. Bonuses get withheld at a flat 22% supplemental rate regardless of your bracket, which overwitholds for lower earners and underwitholds for those above the 24% bracket.
What might change in the next 24 months
Three moving pieces will shape next year's paycheck math. The Social Security wage base climbs annually with the National Average Wage Index: $176,100 in 2025, an estimated $180,000 in 2026 (SSA), and on track for roughly $186,000 in 2027 if the historical 3 to 4% NAWI growth holds. That's the income above which the 6.2% Social Security tax stops, so high earners see a noticeable paycheck bump in the back half of the year.
Federal tax brackets are inflation-indexed, so they shift up by roughly 2.5 to 3% each year and small raises feel less like bracket creep than they used to. The TCJA individual provisions sunset in 2025 was extended for 2026, so the 37% top rate, the $15,000 standard deduction (single), and the elimination of personal exemptions all hold for at least one more year. State-level changes vary: a few states (NY, NJ, CA) added top-bracket surcharges in the past few years, and the AMT phase-out thresholds keep more high-W2 earners out of AMT than the 1990s structure did.