Methodology

How calculations are verified

1. Implement the standard formula for the metric (amortization, BMI, VAT reverse charge, etc.).
2. Cross-check with a second method (spreadsheet or hand calculation) using the same inputs.
3. Document edge cases (zero rates, missing fees, unit mismatches) in Common mistakes.
4. For YMYL topics, cite primary authorities (HMRC, IRS, NHS, CFPB) and label estimates as non-advice.

Sources policy

Prefer primary sources: government agencies, standards bodies (NIST, ISO), and official documentation (MDN, RFCs). Secondary explainers are fine for learning links but should not replace citations on finance or health pages. See also the editorial policy.

Updates & corrections

When tax bands, rates, or unit definitions change, we update the calculator logic and the on-page “Last updated” stamp. If you find an error, contact us via Contact—corrections are prioritized for finance and health tools.

Version history

• 2026-07 — Content & EEAT wave: per-tool editorial insights, answer-first blocks, cited sources, glossary terms, author/reviewer pages, and unique FAQs (no doorway filler).
• 2026-07 — Technical SEO hygiene: robots crawlability for Next assets, apex canonical host, honest structured data, programmatic value tiers, sitemap coverage for EEAT routes.
• Ongoing: rate and guidance updates when primary authorities publish changes; corrections logged via Contact.