UK pension tax relief: relief at source, net pay and salary sacrifice
By GrowThenDraw Editorial Team · Updated August 11, 2026 · 14 min read · Editorial policy
Pension tax relief is often explained as a single percentage. In practice, the cash movement depends on whether a scheme uses relief at source, net pay or a contractual salary sacrifice. The same £10,000 reaching a pension can therefore appear as different deductions and can require different action from the saver.
The linked calculator starts with one gross pension target and keeps the provider addition, Income Tax effect, possible HMRC claim and National Insurance effects separate. It models 2026/27 non-savings income only and is not a tax-return, payroll or suitability decision.
Relief at source: the provider adds basic-rate relief
In a relief-at-source scheme, the contribution shown leaving a bank account or post-tax pay is the net amount. The provider normally claims 20% of the gross contribution from HMRC. A net payment of £8,000 is therefore grossed up to £10,000 by a £2,000 provider addition.
The provider addition is 25% of the net payment but 20% of the gross contribution. Confusing those two bases is a common source of incorrect calculators and pension planning spreadsheets.
Higher and Scottish relief may need a separate claim
The provider normally adds only basic-rate relief. If the gross contribution relieves income taxed at a higher UK or Scottish rate, additional relief may be available from HMRC. That further amount normally reduces the individual's tax liability; it is not another amount automatically deposited by the pension provider.
The calculator estimates the equivalent Income Tax reduction by comparing entered non-savings income before and after the gross contribution. It subtracts the provider addition to show the further relief potentially left to claim. Exact results can change with tax codes, savings, dividends, Gift Aid, other deductions and Self Assessment entries.
Net pay gives Income Tax relief through payroll
Under a net-pay arrangement, the employee contribution is taken before Income Tax is calculated. A £10,000 gross contribution is a £10,000 payroll deduction, but take-home pay normally falls by less because Income Tax is calculated on lower pay.
National Insurance is normally calculated before a net-pay pension deduction. Net pay should therefore not be labelled salary sacrifice and should not be given an employee-NI saving in a calculator.
Salary sacrifice changes contractual cash pay
A successful pension salary sacrifice exchanges future contractual cash salary for an employer pension contribution. Under current 2026/27 rules, Income Tax and category-A employee NI can fall. Employer NI can also fall, but the employer decides whether any saving is added to the pension.
The comparison column is intentionally concise. The dedicated salary-sacrifice calculator adds the employer pay-floor audit, annualised NI bands and the announced April 2029 change. It should be used before treating salary sacrifice as feasible.
Worked comparison: £60,000 income and £10,000 gross target
For an England, Wales or Northern Ireland employee with £60,000 employment income and no other modeled income, an £8,000 relief-at-source payment becomes £10,000 in the pension. The provider adds £2,000. The model's total equivalent Income Tax reduction is £3,946, leaving about £1,946 of further relief potentially to claim and an eventual cash cost of about £6,054.
The same £10,000 net-pay deduction has the same modeled Income Tax effect and about the same eventual cash cost, but there is no provider addition or separate claim. A salary sacrifice also saves about £216.20 of annualised employee NI in this example, reducing the modeled take-home cost to about £5,837.80 before any employer NI sharing.
Adjusted net income can make the effective relief larger
Adjusted net income affects the Personal Allowance taper above £100,000 and the High Income Child Benefit Charge above £60,000. HMRC instructs visitors to deduct the grossed-up amount of relief-at-source pension contributions when working out adjusted net income.
A £10,000 gross contribution from £110,000 of modeled non-savings income can restore £5,000 of Personal Allowance as well as relieve higher-rate income. The calculator reports that effect explicitly and links to the dedicated HICBC calculator rather than folding household Child Benefit assumptions into the pension result.
Relevant earnings and annual allowance answer different questions
Tax relief on an individual's gross personal contributions is normally limited to the higher of relevant UK earnings and £3,600. Employment and trading income can be relevant; pension, dividend and rental income are not automatically relevant earnings. The calculator therefore asks for relevant earnings separately from total taxable income.
The pension annual allowance tests pension input, including employer contributions and defined-benefit growth. The standard 2026/27 allowance is £60,000, but taper, the MPAA and carry forward can change available capacity. Use scheme records and the dedicated carry-forward calculator before relying on a large contribution.
What the comparison deliberately leaves out
The model is annual and includes only entered employment and other non-savings income. It excludes savings and dividend rates, PAYE tax codes, student loans, benefits, multiple employments, exact payroll periods, directors, statutory pay, complete Gift Aid and Self Assessment calculations.
It also cannot decide scheme eligibility, employer permission, National Minimum Wage compliance, relevant-earnings classification, defined-benefit pension input, taper, MPAA, carry-forward membership, annual-allowance charge or whether a contribution is suitable. Those boundaries are more important than a false decimal-place promise.