Methodology & Sources

Every rate and threshold used on this site comes from primary UK government sources. This page explains what we use, how we verify it, and how we handle updates.

Primary source. All PAYE, National Insurance, statutory pay and minimum wage figures come from GOV.UK — principally HMRC's 'Rates and thresholds for employers 2026 to 2027' guidance — rather than third-party summaries. NHS pay scales are sourced from published Agenda for Change tables.

Verification. Each calculator’s formula is written to mirror the published rules (for example, SSP at £123.25 per week or 80% of average weekly earnings if lower, payable from the first day of sickness in 2026/27) and is checked against GOV.UK worked examples where available. Every calculation is reviewed by James Sheridan (CIPP), who cross-checks inputs, outputs and edge cases against the primary source before publication.

Updates. Rates are reviewed at least once per tax year, after the Autumn Budget and the Spring pre-year HMRC publications. The footer of every page states the tax year the figures belong to.

Limitations. Our calculators show estimates for the standard cases. Edge cases — directors' NI, Scottish income tax bands, K codes, student loan deductions — can change the result. Always verify payroll figures against GOV.UK or your payroll software before acting on them.

Corrections. If you spot a figure that looks wrong, tell us via the contact page and we will check it against the primary source.