Sources and rates
Every value the calculator uses, the page or legislation it comes from, and the date it was last checked. Rates are for the 2026-27 tax year (6 April 2026 to 5 April 2027).
| Item | Value | Basis and sources | Last checked |
|---|---|---|---|
| Personal Allowance | £12,570; reduced by £1 for every £2 of adjusted net income over £100,000; nil at £125,140 | Income Tax Act 2007 s 35; GOV.UK | 2 Nov 2026 Read on the official page |
| Income Tax rates (England, Wales, Northern Ireland) | 20% on the first £37,700 of taxable income; 40% to £125,140; 45% above | GOV.UK Income Tax rates; Welsh rates page | 2 Nov 2026 Read on the official page |
| Income Tax rates (Scotland) | 19% to £16,537; 20% to £29,526; 21% to £43,662; 42% to £75,000; 45% to £125,140; 48% above (income with a standard allowance) | GOV.UK Scottish Income Tax | 2 Nov 2026 Read on the official page |
| National Insurance (employee Class 1, category A) | 8% from £12,570 to £50,270 a year, 2% above; weekly £242 and £967; monthly £1,048 and £4,189 | Social Security Contributions and Benefits Act 1992 s 8; GOV.UK employer rates | 2 Nov 2026 Read on the official page |
| Student loans | Plan 1 £26,900, Plan 2 £29,385, Plan 4 £33,795, Plan 5 £25,000 at 9%; Postgraduate Loan £21,000 at 6% | GOV.UK employer rates; GOV.UK student loan repayment | 2 Nov 2026 Read on the official page |
| Pension tax relief | Relief at source: provider adds 20%; net pay: contribution taken before Income Tax; the percentage in the calculator is your choice (5% pre-filled) | GOV.UK pension tax relief | 2 Nov 2026 Read on the official page |
Not included or not confirmed
- No HMRC or official calculator output could be opened to compare with. The engine is checked against hand-worked figures from the published rates and a second, independent implementation, not against an official calculator.
- How Scottish bands apply between 100,000 and 125,140, where the Personal Allowance is reduced: the bands are applied to taxable income after the reduced allowance, with the advanced band ending at taxable income 125,140. The Scottish Rate Resolution text was not opened.
- Relief at source in Scotland: the 20% band is widened by the gross contribution and later bands move up by the same amount. HMRC text on Scottish band extension was not opened.
- Student loan deductions: payroll works out each pay period and rounds down to a whole pound, and the monthly and weekly thresholds are rounded. This site works out the year in one step and rounds down to a whole pound. The two can differ by a few pounds a year. The employer guidance page does not state the rounding rule.
- National Insurance: payroll uses the monthly (1,048) or weekly (242) threshold for each pay period. This site uses the yearly limits, so it can differ from a payslip by under 1 pound a year.
- Income tax is worked out in pence without rounding taxable income down to a whole pound; whether Self Assessment rounds taxable income down was not confirmed.
- Only National Insurance category A is included. Other categories, directors, Class 1A and 1B, employer contributions and the Employment Allowance are not included.
- Not included: salary sacrifice, benefits in kind, tax code adjustments, Marriage Allowance, the High Income Child Benefit Charge, savings and dividend income, Gift Aid, the Blind Person's Allowance, and tax on bonuses paid separately.
- Student loan interest is not included. A Plan loan and a Postgraduate Loan are worked out as two separate deductions from the same pay; the pages that open the HMRC text for combined cases were not read.
Last checked 2 November 2026. These pages give general information. Found a difference from an official page? Tell us.