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RealPaycheckCalculator

Methodology & Sources

Exactly how we turn your inputs into a paycheck estimate, what data we use, and where our estimates can differ from your real pay stub. Last updated October 28, 2026.

Updated Checked against IRS Pub 15-T & state tables

1. Gross pay

Salary ÷ pay periods (52 weekly, 26 bi-weekly, 24 semi-monthly, 12 monthly). Hourly: rate × regular hours × 52, plus rate × overtime multiplier × overtime hours × 52, divided by pay periods. Tips and bonuses entered per paycheck are added to taxable wages.

2. Pre-tax deductions

  • Traditional 401(k)/403(b): reduces federal and state taxable wages (except Pennsylvania), but not FICA wages. Capped at the 2026 limit of $24,500.
  • Section 125 (health premiums, HSA, FSA, commuter): reduces federal, FICA and state wages. California and New Jersey tax HSA contributions.

3. Federal income tax withholding

We follow the IRS Publication 15-T percentage method for automated payroll systems with 2020-or-later Forms W-4:

  1. Annualize taxable wages (per-period wages × pay periods).
  2. Add Step 4(a) other income. Subtract Step 4(b) deductions, including any OBBBA deductions you claim.
  3. Subtract the standard deduction for the W-4 filing status: $16,100 single/MFS, $32,200 MFJ, $24,150 HOH. Married filing separately uses the single table, as in Pub 15-T. If Step 2 is checked, the deduction and bracket widths are halved (the "Step 2 checkbox" tables).
  4. Apply the 2026 brackets, then subtract Step 3 credits ($2,200 per child under 17, $500 per other dependent).
  5. Divide by pay periods and add Step 4(c) extra withholding.

Pub 15-T builds the standard deduction into its table thresholds, which is mathematically equivalent to the steps above.

4. FICA

Social Security: 6.2% of FICA wages up to $184,500. Medicare: 1.45% of all FICA wages, plus 0.9% Additional Medicare Tax withheld on wages above $200,000 regardless of filing status. Per-paycheck figures are annual amounts spread evenly. In reality, Social Security stops entirely once you hit the wage base late in the year.

5. One Big Beautiful Bill Act deductions

When you tick them, we apply the qualified tips deduction (up to $25,000), the qualified overtime deduction (the FLSA premium, up to time-and-a-half, capped at $12,500 / $25,000 joint), the $6,000 senior deduction and up to $10,000 of car loan interest, each with its statutory phase-out based on estimated modified AGI. They reduce federal withholding as Step 4(b) entries would. We assume they don't reduce state tax unless a state has clearly conformed.

6. State income tax

We estimate annual state tax liability: state wages minus the state standard deduction and personal or dependent exemptions, taxed through 2026 state brackets, minus exemption credits. Then we spread it evenly over your paychecks. State-specific rules we model include Alabama's deduction for federal income tax, Oregon's capped federal tax subtraction, Connecticut's exemption phase-out, Wisconsin's sliding standard deduction, Ohio's income-tiered exemptions, Utah's taxpayer credit and Massachusetts' FICA deduction. Head of household filers use single brackets in most states, which may slightly overstate state tax.

Employers calculate state withholding with each state's own formula and withholding certificate, which can differ from liability by a few dollars per paycheck. Over a year, the totals usually come out close.

7. State payroll programs

We include mandatory 2026 employee contributions: CA SDI (1.3%, no cap), NY SDI and PFL, NJ UI/WF, TDI and FLI, WA PFML and WA Cares, Oregon Paid Leave and statewide transit tax, MA, CO, CT, DE, MN and ME paid leave, RI TDI, HI TDI, PA unemployment and AK unemployment. Where employers may split premiums, we assume the maximum employee share.

8. Local taxes

Resident rates for major cities and counties: NYC brackets, Yonkers surcharge, Philadelphia, Pittsburgh, major Ohio and Michigan cities, Maryland and Indiana counties, Louisville, Lexington, Kansas City, St. Louis, Birmingham, Wilmington, Denver and Aurora OPT, and Portland/Multnomah high-income taxes. You can also enter a custom rate. State ranking tables include a typical county tax for Maryland and Indiana only.

Known limitations

  • We don't model state withholding allowances, reciprocity agreements or non-resident rates.
  • The refund estimate in the W-4 calculator doesn't include the EITC, education credits, capital gains or itemized deductions beyond Step 4(b).
  • Some state figures for 2026 are based on the latest published inflation adjustments and may change slightly when states finalize forms.

Testing

Our tax engine is checked against hand-computed results before each release. For example, a $60,000 single filer in Texas withholds $5,020 federal income tax and $4,590 FICA, and California's tax on the same salary is $1,639.53 plus $780 SDI. Corrections are welcome at hello@realpaycheckcalculator.com.