About & Methodology

Data sources (tax year 2026)

• Federal brackets & standard deduction: IRS Revenue Procedure 2025-32 (Oct 2025).
• FICA: SSA 2026 COLA fact sheet — Social Security 6.2% up to $184,500; Medicare 1.45% uncapped; Additional Medicare 0.9% over $200k single / $250k MFJ.
• State income tax: Tax Foundation, “State Individual Income Tax Rates and Brackets, 2026” (as of Jan 1, 2026), which compiles state statutes and forms.

How calculations work

• Annual liability is computed on annualized income, then divided evenly across pay periods (simplified percentage method — IRS Pub 15-T tables are not replicated).
• 401(k)/403(b) deferrals reduce income-tax base but stay subject to FICA; §125 deductions (health premiums, HSA) reduce both.
• State taxable income = gross − pre-tax deductions − state standard deduction − dollar personal exemptions where applicable.

Documented simplifications

• Local income taxes are excluded (NYC/Yonkers, Ohio school districts, Indiana/Kentucky/Maryland counties, Pennsylvania locals, etc.).
• Credit-style exemptions and credits (e.g., Utah taxpayer credit, Arizona dependent credit) are not modeled.
• A few states that tax 401(k) deferrals (PA, NJ) are approximated as conforming.
• State disability/payroll taxes (CA SDI, NJ, WA Cares) are excluded.

Estimates for planning only — not tax, legal or financial advice.