How we calculate
Every result follows the same method payroll software uses, with official 2026 figures. Here is exactly what we do.
Federal income tax
We use the percentage method for automated payroll systems in IRS Publication 15-T (2026), Worksheet 1A, for a Form W-4 from 2020 or later:
- Pay subject to income tax for one paycheck (gross pay minus pre-tax 401(k) and pre-tax benefits), times the number of paychecks in the year.
- Add W-4 Step 4(a) other income; subtract Step 4(b) deductions and the IRS allowance of $12,900 (married filing jointly) or $8,600 (other statuses). The allowance is zero when the Step 2 box is checked.
- Look up the result in the IRS annual table for your filing status (the standard table, or the higher one if Step 2 is checked).
- Subtract W-4 Step 3 credits, divide by the number of paychecks, and add any Step 4(c) extra withholding.
Social Security and Medicare
Social Security is 6.2% of pay up to $184,500 in 2026. Medicare is 1.45% of all pay, plus 0.9% Additional Medicare on pay above $200,000 in the year. Pre-tax health, dental, vision and HSA deductions through a cafeteria (section 125) plan lower these; a traditional 401(k) does not.
A single paycheck shows the early-year amount. When your yearly pay passes the Social Security limit, we say which paycheck it stops at; the yearly totals apply both limits.
State taxes
Florida. Florida has no personal income tax, no employee-paid state payroll tax and no local income tax, so the state line is always $0. Figures checked 2026-09-21.
Texas. Texas has no personal income tax, no employee-paid state payroll tax and no local income tax, so the state line is always $0. Figures checked 2026-09-21.
How we check it
- Our 2026 tables are not typed in and trusted: an automated test rebuilds each one from the brackets and standard deductions in IRS Revenue Procedure 2025-32 and fails if any row differs.
- Worked examples, calculated by hand from the IRS worksheet, run before every update.
- Figures were last checked on the date shown at the top of this page.
What we don't do
We don't cover the older (2019 and earlier) W-4, supplemental-wage flat rates for bonuses paid separately, or states other than Florida and Texas yet. We don't store what you type — the calculator runs entirely in your browser.
Sources
- IRS Publication 15-T (2026), Federal Income Tax Withholding Methods — Worksheet 1A and the annual percentage-method tables
- IRS Publication 15 (2026), Employer's Tax Guide — Social Security and Medicare rates
- Social Security Administration — 2026 wage base of $184,500
- IRS — tips and overtime deductions
- Florida Department of Revenue — Florida does not tax personal income
- Texas Constitution, Article 8, Section 24-a — the legislature may not tax the net incomes of individuals (adopted November 5, 2019)