Methodology and sources
Accuracy is the point of this site. Here is exactly what the calculators do, which rates they use and where they come from.
Income tax
Calculated on taxable income after the personal allowance, with the allowance tapered by £1 for every £2 above £100,000. England, Wales and Northern Ireland use three bands; Scotland uses six.
National Insurance
Employee Class 1 by category letter (A, B, C, H, J, M, V, Z). Employer NI is shown separately and never deducted from your pay.
Student loans
Plans 1, 2, 4 and 5 at 9% and the postgraduate loan at 6% above each threshold, rounded down to the penny.
Pensions
Salary sacrifice reduces pay for tax, NI and loans. Net pay arrangements reduce taxable pay only.
Tax codes
Letter codes (L, M, N, T), 0T, BR, D0, D1, NT and K codes are supported, with S and C prefixes. A code overrides the standard allowance.
Extras
Overtime, bonus, pro-rata hours, Marriage Allowance, Blind Person's Allowance, High Income Child Benefit Charge, self-employed Class 4 NI, Statutory Maternity Pay and two-job tax.
Rates and sources by tax year
UK 2026/27 (6 April 2026 to 5 April 2027)
Last checked 2026-10-08
- https://www.gov.uk/income-tax-rates
- https://www.gov.uk/scottish-income-tax
- https://www.gov.uk/guidance/rates-and-thresholds-for-employers-2026-to-2027
- https://www.gov.uk/government/publications/rates-and-allowances-income-tax/income-tax-rates-and-allowances-current-and-past
- https://www.gov.uk/self-employed-national-insurance-rates
- https://www.gov.uk/child-benefit-rates
UK 2025/26 (6 April 2025 to 5 April 2026)
Last checked 2026-10-08
Ireland 2026 (1 January to 31 December 2026)
Last checked 2026-10-08
Canada 2026 (1 January to 31 December 2026)
Last checked 2026-10-08
- https://www.canada.ca/en/revenue-agency/services/tax/individuals/frequently-asked-questions-individuals/canadian-income-tax-rates-individuals-current-previous-years.html
- https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-contributions/canada-pension-plan-cpp/cpp-contribution-rates-maximums-exemptions.html
- https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-contributions/employment-insurance-ei/ei-premium-rates-maximums.html
- https://www.taxtips.ca/taxrates/canada.htm
- https://www.revenuquebec.ca/en/businesses/source-deductions-and-employer-contributions/employers-kit/principal-changes-for-2026-employers-kit/
Not modelled
- Ireland: medical card USC rate, rent and home carer credits, employer PRSI
- Canada: Quebec is an estimate (EI and QPIP treatment on the Quebec return was not confirmed against Revenu Québec), self-employed Quebec, low-income provincial credits, dependants
- Cumulative PAYE and week-by-week timing
- Benefits in kind and company cars
- Savings and dividend income
- Gift Aid and other reliefs
- Other NI categories (D, E, F, I, K, L, N, S)
- Student loan Plan 3
Results are estimates for information only and not tax advice. If you spot an error please report it; corrections are applied to the shared engine so every page updates together.