How it works
How salary sacrifice works legally
Salary sacrifice (HMRC also calls it “salary exchange” or an “optional remuneration arrangement”) is a formal variation of your employment contract: you agree to a lower cash salary, and your employer provides a non-cash benefit of equivalent value — most commonly paying that amount straight into your workplace pension. Because your contractual pay is genuinely lower, Income Tax and National Insurance are calculated on the reduced figure.
HMRC insists on two conditions for the arrangement to be effective. The contract change must happen before the pay is earned (you cannot sacrifice salary retrospectively), and the sacrifice must be genuine — documented in writing, with your payslip showing the lower cash salary. Your employer must also ensure the arrangement never takes your cash pay below the National Minimum Wage, covered under “the catches” below.
It matters that the money never becomes yours: unlike a normal pension deduction, the sacrificed amount is an employer contribution as far as HMRC is concerned. That is exactly why it escapes National Insurance — and why it interacts with everything from student loans to maternity pay. See the effect on your net pay with the take-home pay calculator.
The double saving: tax AND National Insurance
A normal “net pay” or “relief at source” pension contribution saves you Income Tax. Salary sacrifice saves you Income Tax and National Insurance, because NI is charged on cash earnings and the sacrificed slice is no longer cash earnings. For a basic-rate taxpayer in 2026/27, that means 28% relief at source (20% tax + 8% NI) rather than 20%.
Worked example: you earn £35,000 and sacrifice 5% (£1,750) into your pension. Your taxed salary falls to £33,250. Income Tax drops by 20% × £1,750 = £350 and NI drops by 8% × £1,750 = £140 — a combined saving of £490. So £1,750 goes into your pension but your take-home only falls by £1,260.
There is a third saving that most calculators ignore: employer NI. Your employer pays 15% Class 1 NI on your earnings above £96 a week (2026/27), so the £1,750 sacrifice saves them 15% × £1,750 = £262.50. Many employers pass some or all of this into your pension on top — always ask, because it turns a good deal into an excellent one.
| £35,000 salary, 5% pension | Without sacrifice | With salary sacrifice | Difference |
|---|---|---|---|
| Cash salary for tax/NI | £35,000.00 | £33,250.00 | −£1,750.00 |
| Income Tax | £4,486.00 | £4,136.00 | −£350.00 |
| Employee NI (8%) | £1,794.40 | £1,654.40 | −£140.00 |
| Into your pension | £1,750 (from net/RAS) | £1,750.00 | — |
| Take-home cost of the £1,750 | £1,400 (RAS, after basic relief) | £1,260.00 | −£140.00 |
| Employer NI saved (15%) | £0 | £262.50 | often added to pension |
Basic rate vs higher rate: who saves what
The saving per pound rises with your marginal rate. Above £50,270 the Income Tax rate jumps to 40% while employee NI falls to 2%, so a higher-rate taxpayer saves 42p per £1 sacrificed — and, unlike relief at source, gets all of it automatically through payroll with no self-assessment claim.
| Taxpayer (2026/27) | Tax saved per £1 | NI saved per £1 | Total relief | Net cost of £1 into pension |
|---|---|---|---|---|
| Basic rate (£12,570–£50,270) | 20p | 8p | 28% | 72p |
| Higher rate (£50,270–£125,140) | 40p | 2p | 42% | 58p |
| Additional rate (£125,140+) | 45p | 2p | 47% | 53p |
| £100k–£125,140 (allowance taper zone) | 40p + allowance restored | 2p | up to ~62% | as little as ~38p |
Higher-rate worked example
On £60,000, sacrificing £3,000 saves £1,200 Income Tax (40%) plus £60 NI (2%) — £3,000 lands in your pension for a take-home cost of just £1,740. Compare the bands themselves with the income tax calculator and the national insurance calculator.
What can be salary-sacrificed in 2026/27
Since the 2017 Optional Remuneration Arrangement (OpRA) rules, most benefits bought via salary sacrifice are taxed on the higher of the salary given up or the benefit’s taxable value — killing the tax advantage for things like gym memberships, phones and standard company cars. Four categories were deliberately protected and remain fully effective:
- Pension contributions — the flagship use, with full tax and NI relief as above. Model long-term growth with the pension contribution calculator.
- Electric vehicles — EV leases via sacrifice are taxed only on the Benefit-in-Kind value, just 4% of list price in 2026/27, far below the tax on the salary given up. This is why EV car schemes have boomed.
- Cycle to Work — bikes and safety equipment remain exempt, with tax and NI relief on the hire payments.
- Employer-supported childcare and ultra-low emission vehicles (≤75g CO₂/km) — the remaining protected OpRA categories.
The catches: minimum wage, mortgages, SMP and the annual allowance
Salary sacrifice is a genuine pay cut, and everything keyed to your cash salary sees the lower number. Four consequences deserve attention before you sign.
Also note a confirmed future change: from April 2029, only the first £2,000 a year of pension contributions made by salary sacrifice will be exempt from National Insurance — contributions above that will save Income Tax but not NI. The 2026/27 rules described here are unaffected until then.
- National Minimum Wage floor. Sacrifice can never take your cash pay below the NMW/NLW — £12.71 an hour from April 2026 (about £24,785 a year on 37.5 hours). Employers must block a sacrifice that would breach it; lower earners may need a smaller percentage.
- Mortgage affordability. Lenders assess the post-sacrifice salary on your payslip. Sacrificing £3,000 can cut a 4.5× borrowing multiple by £13,500 — worth pausing large sacrifices in the months before a mortgage application.
- Statutory payments. SMP, SSP and other statutory pay are calculated on your post-sacrifice average earnings. Sacrificing during the 8-week SMP reference window permanently lowers your maternity pay for that leave.
- The £60,000 annual allowance. Sacrificed amounts count as employer pension contributions towards the £60,000 annual allowance (2026/27). Big sacrifices plus employer contributions can breach it, triggering a tax charge — unused allowance from the three previous years can help.
- State pension and benefits. No effect as long as your reduced pay stays above the Lower Earnings Limit — but dropping below it would cost you qualifying years and access to statutory payments.
Salary sacrifice vs relief-at-source pension contributions
Most workplace pensions that do not use sacrifice operate relief at source (RAS): you contribute from taxed pay, and the provider adds 20% basic-rate relief automatically. The differences matter more the more you earn.
Under RAS, a basic-rate taxpayer ends up in nearly the same place except for the NI saving — the 8% that only sacrifice captures. A higher-rate taxpayer under RAS only gets 20% added automatically and must claim the extra 20% through self-assessment (or a tax-code adjustment); an estimated hundreds of millions of pounds of this relief goes unclaimed each year. Salary sacrifice delivers the full 42% instantly through payroll with nothing to claim.
One case where RAS wins: non-earners and very low earners can pay up to £2,880 net (£3,600 gross) into a RAS pension and still get basic-rate relief, while salary sacrifice needs a salary comfortably above minimum wage to sacrifice from. And remember sacrifice reduces student loan repayments too, since those are charged on post-sacrifice gross pay — see the student loan calculator.
Is salary sacrifice worth it?
For most employees saving into a pension anyway, yes — the NI saving is free money, the higher-rate relief is automatic, and any employer NI pass-through compounds it. A basic-rate earner sacrificing £1,750 gains £140 a year versus relief at source; a higher-rate earner sacrificing £5,000 gains £100 in NI plus the certainty of never forgetting a £1,000 self-assessment claim.
The exceptions are earners near the minimum wage floor, anyone about to apply for a mortgage, and anyone about to start maternity leave. In each case the answer is usually to pause or trim the sacrifice temporarily, not to abandon it. Check your own numbers — including the pension pot effect — with the salary sacrifice calculator above.