Methodology

Verified tax-year data

Calculators read rates and thresholds from versioned tax-year configuration files sourced from official publications. We do not invent bands to fill gaps.

Shared engines

Where a guide shows a worked monetary example that depends on tax rules, it should call the same calculation helpers as the live calculator — not a duplicated formula in the article.

Illustrative examples

Some topics (for example Stamp Duty band tables or ISA allowance amounts) are explained structurally and point to GOV.UK for the live figure, so guides do not go stale between Budgets.

Limitations

Estimates may simplify payroll timing, obscure reliefs or edge-case interactions. Each calculator surfaces limitations relevant to that tool.

Read our editorial standards for how guides are reviewed.