Data Sources

How sources are used

Published calculators use country-specific data modules and document assumptions in their page copy. A source supports a rule or threshold; it does not make a simplified calculator an official payroll determination.

United States

• Internal Revenue Service (IRS) federal brackets and deductions.
• Social Security Administration (SSA) contribution and benefit data.
• State revenue department guidance for supported state estimates.

United Kingdom and Ireland

• HM Revenue & Customs (HMRC) payroll and income-tax guidance for UK tools.
• Revenue Ireland guidance for PAYE, USC, and PRSI estimates.

Germany and Netherlands

• German statutory payroll and social-insurance data for 2026 tools.
• Netherlands payroll and wage-tax assumptions documented in the Netherlands data modules.

Spain and Mexico

• AEAT and applicable Spanish payroll guidance for Spain estimates.
• SAT and applicable Mexican payroll guidance for Mexico estimates.

Brazil

• INSS contribution tables.
• Receita Federal monthly IRRF tables and reduction rules.

Review date and limitations

The current release is focused on 2026 data. Source links and access dates are maintained in the repository DATA-SOURCES.md file. Where a complete rule set is not verified, the feature remains simplified, limited, or unpublished.