How we calculate

Every QuidTools calculator runs in your browser using rates we take from official sources. Nothing you type is sent to us. This page explains the main methods and where the figures come from. Figures were last reviewed on 7 November 2026.

Income Tax and National Insurance

We use the HMRC rates and thresholds for the 2026/27 tax year, including Scottish Income Tax bands and the taper of the personal allowance above £100,000. Pay calculators work on a yearly basis by default, as payroll does with a cumulative tax code. Where a single payday matters, for example a bonus, National Insurance and student loan are worked out on that pay period alone, because that is how payroll treats them.

Pensions

Workplace pensions can be taken from qualifying earnings, your whole salary, by salary sacrifice or with relief at source, and each changes what you pay in tax and NI. Public sector schemes (NHS, Teachers’, Police and Civil Service) are net pay arrangements with tiered rates charged on your whole pensionable pay, which we take from each scheme’s published tables.

Public sector pay

Pay scales come from NHS Employers, NHS Wales, NHS Scotland, the School Teachers’ Review Body, the Police Federation and HM Prison and Probation Service. Where an award has been announced but the official scale has not yet been published, we say so on the page. NHS unsocial hours, London weighting and on-call payments follow the Agenda for Change handbook.

NHS Pension projections

Projections are in today’s money. The 2015 scheme builds 1/54 of pay a year, revalued by 1.5% above inflation. The 1995 section builds 1/80 of final salary plus a lump sum of three times the pension, and the 2008 section 1/60. Early and late retirement use approximate factors of 5% a year. The annual allowance check uses the 16 times rule and September CPI.

Contractor and company calculators

Inside IR35 figures assume an umbrella company that pays employer National Insurance and the apprenticeship levy out of the contract rate. Outside IR35 figures assume a £12,570 director’s salary and all remaining profit paid as dividends after Corporation Tax with marginal relief.

Accuracy

Results are estimates for guidance, not financial or tax advice. Your payslip can differ because of your tax code, pay timing, or local terms at your employer. Each calculator lists its sources at the foot of the page. If you spot a mistake, please tell us on the contact page.