Calculator Methodology

Tax year 2026 · Data reviewed 2026-08-15. This page explains exactly how every calculator on this site estimates your paycheck, so you can judge how closely it will match your actual pay stub.

1. Gross Pay

For hourly pay: (hourly rate × regular hours) + (hourly rate × 1.5 × overtime hours), multiplied by 52 weeks, plus any annual bonus entered. For salaried pay: annual salary plus any bonus. Gross pay is then divided evenly across your selected pay frequency (weekly, biweekly, semimonthly, monthly, or annually) — we assume equal pay periods and do not model the extra paycheck that occurs in some years on a weekly or biweekly schedule.

2. Pre-Tax and Post-Tax Deductions

401(k) and "other" pre-tax deductions reduce federal and Arizona taxable wages but not Social Security or Medicare wages, matching how traditional retirement contributions are treated. Health insurance, HSA, and FSA contributions reduce federal, Arizona, Social Security, and Medicare taxable wages, matching Section 125 cafeteria-plan treatment. Post-tax deductions reduce net pay only, after taxes are calculated.

3. Federal Income Tax

We annualize your taxable wages, subtract the IRS standard deduction for your filing status, and apply the 2026 federal tax brackets to the result, then divide by the number of pay periods. This is a simplified annualized-bracket estimate — it is not the IRS Publication 15-T percentage or wage-bracket withholding method your employer's payroll software actually uses, and it does not account for itemized deductions, tax credits, additional W-4 withholding, or multiple jobs.

4. Arizona Withholding

Arizona withholding is calculated as your chosen Form A-4 percentage (0.0%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, default 2.0%) multiplied by your federal-taxable gross wages for the period. This directly matches Arizona's actual A-4 withholding method, which is simpler than federal withholding.

5. Social Security & Medicare (FICA)

Social Security is calculated at 6.2% of wages up to the 2026 annual wage base of $184,500 — we assume consistent annual income to determine when the wage base is reached, which may differ from actual withholding if your pay varies significantly during the year or you change employers. Medicare is calculated at 1.45% of all wages with no cap, plus an Additional Medicare Tax of 0.9% on wages above your filing status's IRS threshold.

6. Rounding & Limitations

• All dollar figures are rounded to the nearest cent internally and to the nearest dollar for display unless otherwise noted.
• This calculator does not account for local court-ordered garnishments, union dues, or employer-specific benefit structures.
• It does not model multiple concurrent jobs, self-employment tax, or non-W-2 income.
• On the main paycheck calculators, a bonus you enter is added to annual ordinary income rather than taxed via the IRS supplemental-wage flat-rate method some employers use for bonuses paid separately — use the dedicated Bonus Tax Calculator for that method (22% federal flat rate, 37% above $1M/year).
• The Arizona Payroll Calculator is employer-facing: it estimates employer-paid costs (matching FICA, Arizona SUTA) on top of wages, and is separate from the employee take-home estimates elsewhere on this site.
• Figures are reviewed annually against IRS, Arizona Department of Revenue, Social Security Administration, Arizona Department of Economic Security, and Industrial Commission of Arizona publications — see Sources.

This calculator provides estimates for general informational purposes only and is not tax, legal, or financial advice. For a definitive calculation, consult your employer's payroll department, a licensed tax professional, or IRS/Arizona Department of Revenue resources directly.