Methodology

One engine per country

Each country has its own calculation engine, because countries differ in more than rates: the order of the steps, what counts as taxable income, how contributions are capped and how amounts are rounded all vary. Engines share only arithmetic helpers. If a country has no engine, there is no calculator for it — we never fall back to another country's rules.

What a result includes

• Income tax at every level we cover for the place you chose.
• Mandatory employee social contributions, such as Social Security, CPP, or German and Polish social insurance.
• Deductions you enter yourself, such as retirement contributions.

Employer-side costs are not deducted from your pay and are not shown. Results assume one job held for the full year and standard allowances; each calculator lists its assumptions under the result.

Verification labels

• Verified — every rate and threshold used was read from an official source for that tax year, and reference calculations were reproduced.
• Unverified estimate — a calculation exists, but at least one rule has not been checked against a current official source. The affected lines are marked.
• Not yet covered / incomplete — a tax or contribution that applies has not been researched. It is listed as “not included” and the total is shown as incomplete. A missing tax is never treated as zero.

Only pages whose rules are verified are submitted to search engines.

How rules are checked

• United States: federal brackets and standard deductions from IRS Revenue Procedure 2025-32; the engine reproduces the tax amounts printed in the IRS rate tables.
• Canada: rates, thresholds and credits from CRA guide T4127; the engine reproduces the bracket constants printed in that guide.
• Germany: wage tax follows the Federal Ministry of Finance payroll algorithm for 2026 and is compared with reference values from the ministry's own calculator.
• Poland: the tax scale from the Ministry of Finance and contribution rates from ZUS, with reference payslips calculated by hand.

The full list is on the tax sources page.

Tax years and versions

Rules are stored per tax year with a version number, an effective period and the date they were checked. When a new year's rules are published, they are added as a new rule set and tested before release; earlier years are not overwritten. Each result shows the tax year and the calculation version it used.

Arithmetic and rounding

Amounts are calculated with decimal arithmetic, not binary floating point. Each country's rounding rules are followed where the law prescribes them — for example German wage tax is rounded down to whole euros and Polish income tax to whole złoty. Monthly and per-paycheck figures divide the annual result evenly, so a real payslip can differ slightly.

Estimate, not an assessment

A salary calculator cannot see your whole situation. Your employer's payroll and the tax authority's assessment are authoritative. Use these results to plan, not to file.