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IRS source documentation
Tax rates, brackets, standard deductions, self-employment tax rules, payroll tax rates, HSA limits, and quarterly due dates are traced to IRS publications, forms, notices, and revenue procedures for the labeled tax year. Calculator pages cite the primary references used.
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Tax engine
Each calculator calls a shared TypeScript tax engine that implements documented formulas. Worked examples on calculator pages use the same engine as the interactive form, so displayed examples match live calculations for the same inputs.
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Annual updates
When IRS guidance updates constants for a new tax year, calculator registries and engine configuration are reviewed. Each calculator displays its tax year and last reviewed date.
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Federal-only scope
Models focus on federal income tax, self-employment tax, and related federal payroll taxes where applicable. State and local taxes are excluded unless a future calculator explicitly states otherwise.
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Simplifications
To keep tools usable for planning, we apply documented simplifications. Warnings on calculator pages describe active simplifications for your scenario—for example, excluded credits, penalty calculations, or eligibility checks not performed.
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No data retention
Calculator inputs are processed in your browser. TaxChecker does not store your inputs on servers as part of standard calculator operation.
Estimates only — not tax advice, legal advice, or financial advice. TaxChecker is not affiliated with the IRS. Consult a qualified tax professional for your situation.
Last updated 2026-06-16