What this calculator is for
Use it to sketch an Income Tax and Class 4 National Insurance bill before you complete a Self Assessment return. The default tax year is 2025/26, which is the year you file by 31 January 2027. Switch to 2026/27 if you want a planning figure for the year that started on 6 April 2026. Pick Scotland when Scottish rates should apply to your non-savings, non-dividend income; otherwise the tool uses the rates for England, Northern Ireland and Wales.
HMRC also publishes its own Self Assessment tax calculator for 2025/26. That official tool assumes the standard Personal Allowance and does not take into account the High Income Child Benefit Charge, income from savings and investments, payments already made towards your next bill, or tax and National Insurance already deducted from employment. Our estimator can include savings and dividends, an optional PAYE deduction and an optional student loan repayment, and it can toggle 2026/27, but it still has important exclusions of its own, listed below.
How the estimate is worked out
All amounts are treated as annual figures in pounds. The tool adds employment, self-employment profit, property profit, pension income, dividends and savings and uses that total as a simple stand-in for adjusted net income when it applies the Personal Allowance taper. It does not subtract pension contributions, Gift Aid or other reliefs, so the taper can be too harsh or too generous if you have those reliefs.
The Personal Allowance is £12,570 in both years. It is reduced by £1 for every £2 of that total above £100,000, and it can fall to zero (which happens at £125,140). The allowance is set against non-savings, non-dividend income first, then savings, then dividends.
Income Tax bands are applied to income after the Personal Allowance, which is how the official rates table is written. For England, Northern Ireland and Wales the bands in both years are: basic rate 20% up to £37,700; higher rate 40% from £37,701 to £125,140; additional rate 45% over £125,141. Scotland has its own starter, basic, intermediate, higher, advanced and top rates, and the starter and basic band widths changed between 2025/26 and 2026/27. Scottish rates are applied only to non-savings, non-dividend income. Savings and dividends always use the UK rates and the UK dividend rates. The calculator will not silently put dividends through the Scottish bands.
Property profit in 2025/26 and 2026/27 is taxed at the main (or Scottish) rates. Budget 2026 Annex A is clear that separate property rates of 24%, 44% and 49% start only from April 2027. This tool does not apply those later rates early.
Savings and dividends
The starting rate for savings is 0% on up to £5,000 of savings income. Taxable non-savings income reduces that band pound for pound, so if taxable non-savings income is £5,000 or more the starting rate is nil. A Personal Savings Allowance is then applied at 0%: £1,000 if total taxable income is in the UK basic-rate band, £500 in the higher-rate band, and £0 in the additional-rate band. For 2026/27 those Personal Savings Allowance amounts are published in Annex A. The official 2025/26 income-tax rates table does not list them; the calculator uses the same frozen amounts and flags that limitation in the result if you are on 2025/26.
The dividend allowance is £500 in both years. Dividend income above the allowance is taxed at 8.75%, 33.75% and 39.35% in 2025/26, and at 10.75%, 35.75% and 39.35% in 2026/27. The allowance is taxed at 0% but still uses up the UK rate band, which is the usual Self Assessment treatment.
National Insurance and student loans
Class 4 National Insurance is charged only on self-employment profit, not on employment, property, pension, dividends or savings. In both years the Lower Profits Limit is £12,570, the Upper Profits Limit is £50,270, and the rates are 6% then 2%. Those 2025/26 Class 4 figures come from the official National Insurance contributions rates table, not from an assumption that the two years are identical. Class 2 is not added as a charge: if profits are at or above the Small Profits Threshold (£6,845 in 2025/26, £7,105 in 2026/27) it is treated as paid; below the threshold you can pay voluntarily, but the estimate does not add that weekly amount unless you arrange it with HMRC.
An optional student loan line uses the official plan thresholds for the year you selected. Plan 5 is offered for 2026/27 only, because the official 2025/26 employer rates table does not publish a Plan 5 threshold. Employees usually repay through PAYE; self-employed repayments are worked out on the return. The figure is a repayment estimate, not a loan balance.
What is left out
The main calculator does not model the High Income Child Benefit Charge, Marriage Allowance, Blind Person’s Allowance, Married Couple’s Allowance, Gift Aid, pension contribution relief, lump-sum payments, or Capital Gains Tax. Residence, domicile, the remittance basis and the trading allowance are also outside its scope. If those items apply, HMRC’s calculation on a filed return, or advice from a qualified person, will differ from this estimate.
When you are ready to file, use the official service and send your return online for free. Software is optional; it is not required to file.