Jonathan Pimperton ACA

Background

I'm Jonathan, an ACA-qualified accountant — the chartered qualification awarded by the Institute of Chartered Accountants in England and Wales (ICAEW) — with professional experience across UK, US, and Australian tax systems. I built CalcRun because most online calculators are ad-heavy, outdated, or won't show their working.

That background matters for a site like this: take-home pay, mortgage amortisation, and investment growth all hinge on rates and thresholds that change every year, and a wrong figure is worse than no figure. Treating rate verification as an accounting exercise — source, check, date-stamp — is the core of how this site is run.

Editorial standards

• Every tax rate and threshold is sourced from official data — HMRC and GOV.UK for the UK, the IRS and SSA for the US — and each rate-dependent calculator shows its sources and the date they were last verified (UK rates: 2026/27, last checked 2 July 2026; US rates: 2026).
• Formulas are documented on public methodology pages — every financial calculator links to its own "How we calculate this" page (for example, compound interest) — so every result can be checked by hand.
• Scenario and comparison figures are computed with the same engines that power the calculators, not copied from third-party articles.
• An automated freshness guard fails the site build when a tax year rolls over, so stale rates cannot silently ship.
• Affiliate partnerships never change a number. Recommendations sit after the answer, are labelled, and are covered by the affiliate disclosure.