How to Calculate US Take-Home Pay in JavaScript (2026 Tax Brackets)

If you've ever built a payroll feature or a salary calculator, you know that "take-home pay" is deceptively complex. Federal brackets, FICA taxes, state taxes — each layer has its own rules. In this post, I'll walk through the actual math and show you a clean JavaScript implementation.

Want the answer without the code? Try the free US Paycheck Calculator — no signup, 2026 rates built in.

The layers of US payroll tax

For a typical W-2 employee, gross pay is reduced by:

Federal income tax — progressive brackets (10% to 37%)
Social Security — 6.2% on the first $176,100 (2026 wage base)
Medicare — 1.45% on all wages, plus 0.9% additional Medicare tax above $200,000
State income tax — varies wildly; some states have none

Federal income tax (single filer, 2026)

const FEDERAL_BRACKETS_SINGLE_2026 = [
  { upTo: 11925, rate: 0.10 },
  { upTo: 48475, rate: 0.12 },
  { upTo: 103350, rate: 0.22 },
  { upTo: 197300, rate: 0.24 },
  { upTo: 250525, rate: 0.32 },
  { upTo: 626350, rate: 0.35 },
  { upTo: Infinity, rate: 0.37 },
];

function federalTax(income, brackets) {
  let tax = 0;
  let prevLimit = 0;
  for (const { upTo, rate } of brackets) {
    if (income <= prevLimit) break;
    const taxableInBracket = Math.min(income, upTo) - prevLimit;
    tax += taxableInBracket * rate;
    prevLimit = upTo;
  }
  return tax;
}

FICA taxes

function ficaTax(grossPay) {
  const socialSecurity = Math.min(grossPay, 176100) * 0.062;
  let medicare = grossPay * 0.0145;
  if (grossPay > 200000) {
    medicare += (grossPay - 200000) * 0.009;
  }
  return socialSecurity + medicare;
}

Putting it together

function takeHomePay(grossPay, stateTax = 0) {
  const federal = federalTax(grossPay, FEDERAL_BRACKETS_SINGLE_2026);
  const fica = ficaTax(grossPay);
  return grossPay - federal - fica - stateTax;
}