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Finance & LoansGenerated accuracy model review: 2026-05-06

Income Tax Estimator accuracy and testing

This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.

Formula source

  • The US uses a progressive tax system. You don't pay 22% on *all* your income just because you are in the 22% bracket. You pay 10% on the first chunk, 12% on the next, and 22% only on the amount above the threshold.

Test cases

Default input regression check

Generated from the checked-in default inputs and calculate function.

Inputs

  • Federal Tax Table: irs_2026
  • Gross Annual Income: $75,000
  • Filing Status: Single
  • State Tax Add-on: state_none
  • Custom Federal Rate: 15%
  • Custom State Rate: 0%

Expected outputs

  • Estimated Federal Tax: $7,670.00
  • Estimated State Tax: $0.00
  • Estimated Total Tax: $7,670.00
  • Effective Tax Rate: 10.23%
  • Annual After-Tax: $67,330.00

Known limitations

  • Does not account for credits (like Child Tax Credit), itemized deductions, or State/Local taxes.

Assumptions

  • Inputs are interpreted exactly as entered in the calculator form.
  • The calculation runs locally in the browser using the current checked-in calculator definition.

Unit handling

  • Federal Tax Table accepts one of the configured options.
  • Gross Annual Income accepts values in $.
  • Filing Status accepts one of the configured options.
  • State Tax Add-on accepts one of the configured options.
  • Custom Federal Rate accepts values in %.
  • Custom State Rate accepts values in %.
  • Estimated Federal Tax is displayed as currency.
  • Estimated State Tax is displayed as currency.
  • Estimated Total Tax is displayed as currency.
  • Effective Tax Rate is displayed as a percentage.
  • Annual After-Tax is displayed as currency.

Rounding rules

  • Number displays use up to 2 decimal places in the calculator UI.
  • Currency outputs are displayed with standard US dollar formatting.
  • Percent outputs are displayed with two decimal places.
  • Input precision follows configured step values where provided.

Version history

1.0.0 - 2026-05-06

Generated accuracy and testing page from the current income-tax-calculator calculator definition.

Change log

2026-05-06

Published default regression test documentation and metadata fallbacks for Income Tax Estimator.

Calculator transparency

Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.

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