Trust & methodology

Data Sources

Every figure in a KalkWise calculator traces to an authoritative source. This page lists what we use, where it comes from, and how often it is reviewed. Last updated June 2026.

Federal income tax

Annually (new tax year)

Tax brackets, standard deductions, filing-status thresholds

Source: Internal Revenue Service (IRS)

FICA / payroll taxes

Annually

Social Security rate (6.2%) and wage base, Medicare rate (1.45%) and additional Medicare surtax

Source: Social Security Administration (SSA) & IRS

Retirement contribution limits

Annually

401(k), IRA, Roth IRA, HSA contribution limits and catch-up amounts; RMD tables

Source: IRS (notices & publications)

State income tax

Annually + after legislative changes

State brackets and flat rates used in paycheck, income tax, and self-employment calculators

Source: State revenue departments; Tax Foundation summaries

State sales tax

Annually

Combined state + average local sales tax rates for all 50 states

Source: Tax Foundation (2025 mid-year rates)

Social Security benefits

As rules change

Claiming-age adjustment factors, full retirement age rules

Source: Social Security Administration (SSA)

Inflation

Reviewed annually

Historical CPI used for inflation and real-return calculations

Source: U.S. Bureau of Labor Statistics (CPI-U)

Mortgage & loan math

N/A — formulas are exact

Amortization, payment, and payoff formulas

Source: Standard actuarial formulas (no external data needed)

FHA / loan program rules

As programs change

FHA MIP rates, down-payment minimums

Source: U.S. Department of Housing and Urban Development (HUD)

Found a figure that looks out of date? Tell us — confirmed data corrections are prioritized over all other work. See also our Editorial Policy and Disclaimer.