Data Sources

Every primary regulator, Big-4 tax firm, and industry framework we cite across our calculators and content. We treat citation transparency as a first-class quality signal — both for human readers and for AI engines summarising our work.

If a number you read on this site doesn't reconcile with one of these sources, please email our team — we re-verify quarterly.

Regulators & primary law

Tax authorities & Big-4 commentary

International frameworks