Accuracy & sources

Every rate and threshold on this site is sourced from published government material, primarily HMRC rate tables on GOV.UK and the relevant legislation. We do not generate calculator figures from language models or unverified sources.

Primary sources

• GOV.UK: Income Tax rates and personal allowances
• GOV.UK: National Insurance rates and categories
• GOV.UK: Repaying your student loan
• GOV.UK: HM Revenue & Customs

What we verify

• Income tax bands, personal allowance and the £100,000 taper (England/Wales/NI and Scotland separately).
• Class 1 National Insurance thresholds and rates.
• Student loan thresholds and rates for Plans 1, 2, 4 and 5, and the postgraduate loan.
• Pension contribution rules for each method.

Versioning

Rates are versioned by tax year. When a new tax year's figures are announced we add them and mark any forward-projected figures as estimated until confirmed. Each calculation page shows which tax year it is using.

Rounding & timing

Income tax uses cumulative PAYE across the year; National Insurance and student loans use per-pay-period (monthly) thresholds, exactly as HMRC applies them. Figures are rounded to the nearest penny. Your exact take-home may differ if your employer uses different pensionable-pay rules or you have a non-standard tax code.