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NetPayFinder

How we calculate

The method behind every NetPayFinder result for 2026/27, step by step.

Rates were last verified against HMRC on 5 October 2026. Changes are listed in ourrates changelog.

The calculation, step by step

  1. Yearly pay. We turn what you enter into a yearly salary: monthly × 12, every 4 weeks × 13, weekly × 52, daily × days per week × 52, hourly × hours per week × 52. A one-off bonus is added on top.
  2. Pension. A percentage contribution is worked out on your salary (not the bonus), or on qualifying earnings between £6,240 and £50,270 if you choose that option. A £ amount is used as entered.
  3. Salary sacrifice (pension or other schemes) reduces your gross pay before tax, National Insurance and student loan.
  4. Net pay pensions are taken off before income tax. Relief at source pensions are paid from take-home pay at 80% of the gross amount, because your provider adds 20% basic-rate relief.
  5. Taxable pay is pay after salary sacrifice and net pay pension, plus any taxable benefits such as a company car.
  6. Personal Allowance. With the standard tax code (1257L) you get £12,570tax-free. It goes down by £1 for every £2 of adjusted net income over £100,000 (so it reaches zero at £125,140), rounded to whole pounds as the law requires. Relief at source contributions reduce adjusted net income. Blind Person’s Allowance and Marriage Allowance adjust it when you select them.
  7. Your own tax code. If you enter a different code we use it exactly: the number × 10 is your allowance (for example 1100L = £11,000). HMRC has already built your allowances and adjustments into it. K codes add to taxable pay, and tax is capped at 50% of pay. BR, D0, D1 and the Scottish SBR and SD codes tax all pay at one rate. NT means no tax, and 0T means no allowance.
  8. Income tax is charged band by band on taxable income above the allowance, using Scottish bands if you live in Scotland or your code starts with S. Welsh rates (C codes) are currently the same as England’s. Tax in each band is rounded to the nearest penny.
  9. Extra pension relief. Higher-rate taxpayers with relief at source pensions can claim more relief through Self Assessment. We show this separately; it isn’t included in take-home pay.
  10. National Insurance (category A) is 8% of earnings between £12,570 and £50,270 and 2% above, on your pay after salary sacrifice. Pension contributions under net pay or relief at source don’t reduce it. Employees over State Pension age pay none.
  11. Student loans are worked out on the same pay as National Insurance. If you have more than one undergraduate plan, one repayment is taken against the lowest threshold and shared between plans, as HMRC’s guidance describes. A Postgraduate Loan is repaid separately at its own rate.
  12. Take-home pay is what remains after all of the above. Monthly, weekly and daily figures are the yearly figure divided evenly.

Assumptions

What we don’t model

How we test

The calculator is checked automatically before every release against 175 worked examples across 2 tax years, covering every tax band boundary, the allowance taper, each student loan plan, pension types and tax codes.30 of them are cross-checked against an independent calculator. If any test fails, the site isn’t updated.

Sources

We use only official sources, and record when we last checked each one.