What does your next £1 of pay actually cost you — and what is £1 into your pension really worth? Income tax, National Insurance, student loans, the 60% trap and the child benefit charge, all in one honest picture. Nothing you enter leaves your browser.
Tax year and scope. 2026/27, England, Wales & Northern Ireland. Personal allowance £12,570, tapered £1 per £2 of adjusted net income above £100,000 (gone at £125,140). Taxable income: 20% on the first £37,700, 40% to £125,140, 45% above. Scottish income tax uses different bands and rates (19%–48%) and is not modelled; National Insurance and student loans below are UK-wide. Assumes a standard 1257L tax code, no benefits in kind, and income from salary only.
National Insurance. Employee Class 1 at 8% between £12,570 and £50,270 and 2% above, annualised. If you are over State Pension age you pay no employee NI — subtract the NI line.
Student loans. 9% of pay above the plan threshold (Plan 1 £26,065, Plan 2 £28,470, Plan 4 £32,745, Plan 5 £25,000); postgraduate loans 6% above £21,000, on top. These are the April 2025 confirmed thresholds; Plans 1, 2 and 4 rise with RPI each April — check gov.uk for the current figures. If you hold two undergraduate plans, repayments still total 9% (split between them), so pick your main one.
High-income child benefit charge. Child benefit taken as £27.05/week for the first child and £17.90 for each other (April 2026 uprating applied to the 2025/26 rates — verify on gov.uk). The charge claws back 1% of it per £200 of adjusted net income over £60,000, all of it at £80,000. We show the charge as a smooth taper; in reality it moves in £200 steps (at most one step, roughly £23 for two children, from what's shown). Salary sacrifice and gross personal pension contributions both reduce adjusted net income, which is why they can restore child benefit.
Pension contributions. Salary sacrifice reduces pay before tax, NI and student loans. Personal (relief-at-source) payments are grossed up by 25%, extend the basic-rate band and the additional-rate threshold, and reduce adjusted net income — capturing the higher-rate relief you claim back through a tax return. Net-pay workplace schemes (full tax relief through payroll, no NI saving) are not separately modelled. The £60,000 annual allowance (tapered for the highest earners) and the minimum-wage floor on sacrifice are not enforced here — check before making large contributions.
Marriage Allowance. If ticked, a £252 tax reduction (20% of the £1,260 transferable allowance), applied only while you pay no more than basic rate — the eligibility condition. The marginal-rate chart and headline exclude it because it is a flat credit, not a rate: losing it on crossing into higher rate is a one-off £252 cliff, which the "At your salary" panel flags instead.
What "marginal rate" means here. The pence lost from the next £1 of gross pay across income tax, NI, student loan and the child benefit charge together. It is not what HMRC calls your tax band, and cliff-edges that aren't rates (free childcare hours and tax-free childcare, both lost above £100,000 adjusted net income; Marriage Allowance) are flagged in the text rather than drawn on the chart.
This tool provides general information and education, not financial advice, tax advice or a personal recommendation. Figures refer to the 2026/27 tax year under the stated assumptions; payroll software, tax codes and individual circumstances differ. Check gov.uk or a qualified adviser before acting.