UK Marginal Deduction Rate Calculator — 2026/27
Your marginal rate is what you lose from your next £1 of salary — not your average tax rate, which is usually much lower. It's rarely a flat 20% or 40%: the personal allowance taper between £100,000 and £125,140 creates the well-known zone where well over half of extra earnings can disappear, and a student loan plan adds a further chunk on top. This tool sweeps your salary from £0 to £200,000 in £500 steps using 2026/27 tax year rates for England, Wales & Northern Ireland, and plots your marginal rate at every point so you can see exactly where the cliffs are.
Shows your marginal deduction rate — the share of your NEXT £1 of salary lost to tax, NI, student loan and the Child Benefit charge — across the £0–£200,000 salary range, using 2026/27 rates for England, Wales & Northern Ireland.
Enter your salary details and select Calculate to see how your marginal deduction rate changes across the salary range.