How UK pension salary sacrifice compares to relief at source

People often ask “sacrifice or relief at source?” as if those were the only two boxes. GOV.UK’s workplace-pension pages describe two automatic ways to get Income Tax relief: net pay, and relief at source. Salary sacrifice is a separate contract change that can sit on top of a workplace scheme. Check your scheme booklet or payslip rather than guessing from the provider’s brand name.

Under a net pay arrangement the employer takes the contribution before Income Tax. You only pay tax on what is left, so higher-rate and additional-rate relief arrive through PAYE. The amount on the payslip is usually the contribution plus that tax relief. If you earn below the Personal Allowance you typically get no tax relief under net pay, because there was no tax to refund.

Under relief at source the employer takes the contribution after tax and National Insurance. The provider then adds basic-rate relief (20% in this site’s rUK model) to the pot. The payslip shows only what left your pay, not the top-up. Higher-rate and additional-rate taxpayers claim the extra slice on a Self Assessment return or through HMRC’s standalone claim. People who pay little or no Income Tax can still receive the 20% top-up on modest contributions — that is the usual reason a very low earner is better off in a relief-at-source scheme than in net pay.

Salary sacrifice is not “a type of tax relief”. It is an agreement to reduce cash pay in return for a non-cash benefit. For a registered pension that benefit is still one of the items HMRC lists as keeping its tax and NI exemption when it is provided through sacrifice (alongside things such as cycle-to-work and workplace nurseries). PAYE then runs on the lower cash salary. You cannot flip in and out week by week: HMRC’s employer guidance says a genuine variation of the contract is required, and freely swapping cash for a benefit can undo the tax and NI treatment.

Income Tax relief on a pension contribution is not unique to sacrifice. Net pay gives it through payroll. Relief at source gives basic-rate relief in the pot and higher-rate relief if you claim it. Sacrifice gives it because the salary those bands are applied to is smaller. Compare the same pounds landing in the pension and the Income Tax line is often identical. The line that moves is employee National Insurance.

Our calculator does not simulate the relief-at-source cashflow (you pay 80p, HMRC adds 20p). It holds the pot contribution fixed and asks a narrower question: are Income Tax and employee NI both calculated on the reduced salary, or is tax relief given while NI stays on the full contractual pay? For a basic-rate taxpayer that second path is economically the same as true relief at source after the 20% is added. For a higher-rate taxpayer it assumes the extra tax relief arrives — immediately under net pay or sacrifice, later under relief at source if you claim it.

Employer Class 1 NI is a third saving, and it is a cost to the business, not a line on your payslip. On this site’s 2026/27-style model the employer rate is 15% of earnings above £5,000. Some employers pay part of that saving into your pension; others keep it. The calculator shows the illustrative employer figure separately and does not add it to take-home.

This is the default on our salary-sacrifice calculator (England, Wales and Northern Ireland, no student loan). Start with no pension. Income Tax is £6,486 and employee NI is £2,594.40. Take-home is £35,919.60 — the same split as the take-home guide’s £45,000 walk-through.

Now put 5% — £2,250 — into the pension by salary sacrifice. Cash pay for tax and NI becomes £42,750. Income Tax falls to £6,036, a £450 saving, which is simply 20% of £2,250. Employee NI falls to £2,414.40, a £180 saving, which is 8% of £2,250. Take-home is £34,299.60. You put £2,250 into the pot; the bank account only dropped by £1,620. Tax and NI covered the other £630.

The same £2,250 modelled without sacrifice still saves the £450 of Income Tax, but employee NI stays at £2,594.40. Take-home is £34,119.60 — £180 less than the sacrifice path. That £180 is the whole extra take-home from sacrifice at this salary. It is not a mystery bonus. It is the employee NI that sacrifice no longer charges on the contributed pounds.

Illustrative employer NI on the same numbers falls by £337.50 (15% of £2,250). Whether any of that reaches your pot is a scheme decision, not a tax law automatic.

On £60,000 with an 8% sacrifice (£4,800) almost all of the efficiency versus no pension is 40% Income Tax relief: £1,920. Employee NI only falls by £96, because those pounds sit above the Upper Earnings Limit where the employee rate is 2%, not 8%. Take-home with sacrifice is £42,573.40 against £45,357.40 with no pension — a net cost of £2,784 to put £4,800 in the pot.

Extra take-home versus the same pot without sacrifice is that £96 of NI. If your scheme is relief at source and you are a higher-rate taxpayer, you still need to claim the extra 20% or the comparison in your head will flatter sacrifice. Sacrifice and net-pay arrangements usually deliver that higher-rate relief through PAYE instead of a later claim.

Scotland uses different Income Tax bands; National Insurance is still UK-wide. Switch the region on the calculator rather than scaling the rUK table. Starter-rate Scottish taxpayers still see providers claim relief at source at 20% — you do not have to pay the 1% difference back.

At exactly £100,000 this model still gives the full £12,570 Personal Allowance. A 5% sacrifice (£5,000) saves £2,000 of 40% tax and £100 of 2% NI. Type a figure above £100,000 if you want to see the taper: each £2 of extra income removes £1 of allowance, so the effective Income Tax rate on that slice is often described as 60%.

Sacrifice that pulls contractual pay back toward £100,000 can restore some of that allowance. The calculator applies the taper to the pay figure used for tax in each scenario. Real adjusted net income can include other items (Gift Aid is the usual extra), so treat that zone as a reason to check a payslip and the Personal Tax Account, not as a finished computation.

The usual Annual Allowance — commonly £60,000 of pension input, with a taper for very high incomes — is not modelled. Protected tax-free cash, scheme charges and recycling rules are also out of scope.

HMRC’s employer guidance is blunt: a sacrifice must not take cash earnings below the National Minimum Wage. Payroll should cap the deduction. If you are close to that floor, the arrangement may be refused or trimmed, whatever the calculator says.

Statutory payments (maternity, paternity, shared parental, sick pay) use average weekly earnings tests. If sacrifice pulls those earnings below the Lower Earnings Limit, some people lose entitlement altogether. Occupational maternity pay, overtime and pay rises may be calculated on the reduced cash salary or on a notional pre-sacrifice figure — that has to be written down, not assumed. MoneyHelper also flags smaller mortgages and smaller salary-linked life cover as the everyday reasons people pause before exchanging pay.

Student loan deductions use their own income thresholds. A lower cash salary can reduce a PAYE deduction; Self Assessment still looks at the year as a whole. Model the loan on its own calculator with the income figure that applies to your plan, then combine with care. Statutory redundancy pay is a separate weekly-pay calculation — if your employer uses the reduced contractual wage, the statutory estimate can move.

Because a sacrificed pension contribution is usually treated as an employer contribution, the money is typically locked in until the scheme’s minimum pension age (55 today; 57 from April 2028 for most people). Employee contributions to a defined-contribution pot can sometimes be refunded if you leave quickly. That refund window is another reason “the same pounds in the pot” is not the whole decision.

The government has legislated to cap the National Insurance exemption on employee pension contributions made by salary sacrifice. From April 2029 only the first £2,000 a year of those sacrificed employee contributions stays NI-free. Income Tax relief is unchanged. You can still sacrifice more than £2,000; employee and employer NI will apply to the excess, in line with other employee workplace contributions. Ordinary employer pension contributions that are not employee sacrifice stay NI-free.

GOV.UK’s own note is that most people making typical auto-enrolment-style contributions will not be affected. An 8% sacrifice on a £60,000 salary is already well above £2,000, so that extra NI advantage shrinks in 2029/30. Our calculator does not model the cap. Until April 2029 the NI figures in the worked examples are the current 2026/27-style treatment.

Open the salary-sacrifice calculator, enter contractual gross pay, pick England/Wales/NI or Scotland, and enter the employee amount as a percentage or a fixed £ figure. The first result card is take-home with sacrifice. The second is the net cost versus no pension. The third is the same contribution without sacrifice. Optionally add an employer pension percentage to see total money into the pot — that employer slice is not the same as any NI-sharing arrangement.

Then run take-home pay if you want the no-pension tax and NI split on its own, National Insurance if you are costing a hire, and the student loan calculator if you have a plan. Nothing you type is stored. If the payslip disagrees, the payslip and the scheme booklet win.