The thresholds it uses
Nothing is due on the first £12,570, then 8% up to £50,270, and 2% on anything above that.
A worked example
On a £35,000 salary the charge is £1,794.40, an effective rate of 5.1% even though the marginal rate is 8%.
Marginal and effective rates differ
The marginal rate is what the next pound costs; the effective rate is the whole bill divided by the whole salary. Confusing the two overstates what a raise really costs.
The 2% band is not a cap
Above the upper threshold the rate drops, but it never stops. High earners keep paying, just more slowly.
This is not your whole deduction
Income tax comes on top, and so do pension contributions and any student loan repayment. Your payslip nets all of them together.
Your employer pays too
Employer National Insurance is a separate charge at a different rate, and it does not appear on your payslip at all.
Class 1 is for employees only
The self-employed pay under different classes with their own thresholds, so this figure will not match a sole trader's bill.
Contributions build entitlement
Qualifying years count towards the State Pension and some contributory benefits, which is why the record matters beyond the deduction itself.
Directors are calculated annually
Company directors use an annual earnings period rather than a per-pay-period one, so mid-year figures can look very different.
How much one input matters
Raise annual salary by 10%, from £35,000 to £38,500, and the result moves from £1,794.40 to £2,074.40, a change of +15.6%. It marks the input worth verifying first.
Check the current year before relying on it
Thresholds and rates are set at fiscal events and do change. HMRC and your payslip remain the definitive sources. Many payslip queries come down to confusing the marginal rate with the effective one: the first is what the next pound costs, the second is the whole bill spread across the whole salary. Above the upper earnings limit the rate falls to two per cent but never stops, so higher earners keep contributing at a slower pace. Income tax sits on top of this figure, and pension contributions and student loan repayments are netted alongside it on the payslip. Employer contributions are charged separately at their own rate and never appear on the employee payslip at all. The self-employed contribute under different classes with their own thresholds, so a sole trader bill will not match this one. Qualifying years build entitlement to the State Pension and several contributory benefits, which is why the contribution record matters. Company directors are assessed on an annual earnings period rather than each pay period, so mid-year figures can look unusual. Thresholds and rates are set at fiscal events and do change, so the current year should always be confirmed before relying on any estimate. Confusing the marginal rate with the effective one overstates what a pay rise actually costs in contributions. The contribution record is what builds entitlement, so gaps in qualifying years matter long after the deduction itself is forgotten.