Methodology & sources
UK Pay Calculator is an independent calculator. The aim is to provide a clear annual estimate using published 2026/27 UK tax and payroll rules, while being explicit about the assumptions that can make a real payslip differ.
Tax year
The calculator currently uses the 2026/27 tax year, running from 6 April 2026 to 5 April 2027.
Income Tax
For England, Wales and Northern Ireland, the calculator applies the standard Personal Allowance and the basic, higher and additional Income Tax bands. For Scotland it uses the separate starter, basic, intermediate, higher, advanced and top rates.
The standard Personal Allowance is reduced by £1 for every £2 of adjusted income above £100,000 and reaches zero at £125,140.
National Insurance
Employee Class 1 National Insurance is estimated using category A rates: 8% in the main band and 2% above the Upper Earnings Limit. The main calculator annualises these thresholds, so payroll rounding by week or month can produce small differences.
Pensions
The calculator treats pension methods separately because they affect payroll differently:
- Salary sacrifice: the sacrificed amount reduces pay used for Income Tax, National Insurance and student-loan calculations.
- Net pay: the contribution reduces pay before Income Tax, while National Insurance and student-loan calculations continue to use unreduced pay.
- Relief at source: the contribution is taken after PAYE and National Insurance. The calculator treats the amount entered as the gross pension contribution and assumes the provider adds basic-rate tax relief, so the employee cash cost is normally 80% of that gross contribution.
For relief-at-source contributions, the calculator does not assume that higher- or additional-rate tax relief has already been claimed through a tax-code adjustment or Self Assessment.
Student loans
Plan 1, Plan 2, Plan 4 and Plan 5 repayments are estimated at 9% above the relevant annual threshold. Postgraduate Loans are estimated separately at 6% above their threshold.
Testing
The tax engine has automated regression tests covering the Personal Allowance, higher-rate threshold, Personal Allowance taper, Scottish tax bands, student loans and each supported pension arrangement. Those tests run automatically before every production build.
Official sources
- GOV.UK — Income Tax rates and Personal Allowances
- HMRC — Rates and thresholds for employers 2026 to 2027
- Scottish Government — Scottish Income Tax rates and bands 2026/27
- GOV.UK — Student loan repayment thresholds and rates
- GOV.UK — Workplace pension tax-relief arrangements
- HMRC — Adjusted net income
Rates and assumptions were checked against the official sources above. UK Pay Calculator is not an HMRC service and the figures are estimates rather than tax or financial advice.