Guide
Salary sacrifice, and exactly what it saves
You give up salary; your employer pays it into your pension instead. Because your contractual pay genuinely falls, National Insurance falls with it — and that is the part a personal contribution cannot do.
A personal pension contribution gets you income tax relief. A salary sacrifice contribution gets you income tax relief and the National Insurance, on both sides. That is the whole difference, and at some incomes it is worth thousands a year.
The mechanism is simple: you agree a lower salary, and your employer pays the difference into your pension. Because the sacrificed amount was never earnings, no income tax and no National Insurance is due on it — not yours (8% or 2%) and not your employer's (15%).
What £5,000 sacrificed is worth
| Salary | Take-home given up | Into the pension | Cost per £1 of pension | Employer NI saved |
|---|---|---|---|---|
| £30,000 | £3,600 | £5,000 | £0.72 | £750 |
| £50,000 | £3,600 | £5,000 | £0.72 | £750 |
| £60,000 | £2,900 | £5,000 | £0.58 | £750 |
| £80,000 | £2,900 | £5,000 | £0.58 | £750 |
| £110,000 | £1,900 | £5,000 | £0.38 | £750 |
The fourth column is the real price: how much spending power you give up to put £1 into your pension. Lower is better, and it is lowest exactly where the marginal rate is highest.
At £110,000 — inside the allowance taper — £5,000 into the pension costs £1,900 of take-home. That is the best trade available in UK personal finance, and it exists only because the marginal rate there is 62%.
The employer's side
Sacrifice saves the employer 15% of the sacrificed amount in National Insurance. Many employers pass some or all of that saving into the pension too, which improves the trade further — it is worth asking, because a scheme that does not mention it usually keeps it.
What to watch
- You cannot sacrifice below the National Minimum Wage. Schemes will refuse the contribution rather than break the floor.
- Your salary is genuinely lower for anything referenced to salary — mortgage affordability, death-in-service cover, redundancy pay, and statutory maternity pay, which is calculated on post-sacrifice earnings. Some employers write around this with a "notional salary"; many do not.
- Lower earnings can reduce state benefits. Sacrificing below the NI lower earnings limit affects your State Pension record.
- The annual allowance caps total pension input, and it tapers for high earners. Exceeding it creates a tax charge that can undo the whole saving.
None of this is advice, and pension decisions are the kind that deserve a qualified adviser. The arithmetic above is the part this site can do reliably.
A note on the employer's share
The National Insurance an employer saves on a sacrificed amount is theirs unless the scheme says otherwise. Many employers pass some or all of it into the pot, which materially improves the deal, and the scheme rules will say which. It is worth asking before assuming either way.
The one case where it is clearly the wrong move
If sacrificing would take your pay below the National Minimum Wage, the arrangement is not permitted — an employer cannot lawfully sacrifice you under the floor, and a scheme that appears to allow it is misconfigured. Short of that, the awkward case is someone close to a mortgage application: lenders assess affordability on the reduced contractual salary, and a sacrifice agreed three months before an application can cost more in borrowing capacity than it saves in tax. The tax arithmetic is only one side of that decision, and it is the side this page can compute.
Why sacrifice beats an ordinary contribution
Both routes get money into a pension with income tax relief. Only sacrifice avoids National Insurance, and it avoids it twice — the employee's, and the employer's fifteen per cent on the sacrificed amount. That second saving is the reason many employers pass some or all of it into the pot: it costs them nothing to do so and it makes the arrangement obviously worthwhile for the employee.
The size of the advantage depends on where you are. Below the National Insurance upper earnings limit the employee saves 8% on top of income tax relief; above it, only 2%. So sacrifice is proportionally most valuable in the band just below the upper earnings limit, and its advantage narrows above it — which is the opposite of what most people assume.
What to check before agreeing to one
Sacrifice reduces your contractual gross pay, and a number of things are calculated from that figure rather than from your notional salary. Mortgage affordability assessments usually work from the reduced figure. Statutory maternity, paternity and sick pay entitlements are based on earnings, so a large sacrifice can reduce them. Life cover expressed as a multiple of salary may be reduced unless the scheme defines salary as pre-sacrifice — most good ones do, but it is worth reading. And you cannot sacrifice below the National Minimum Wage, which caps the arrangement for lower-paid workers.
None of these makes sacrifice a bad idea. They are the reasons it is a decision rather than an automatic yes, and they are the questions worth asking your employer before signing the variation.
Checking this against your own payslip
Everything above is arithmetic on published parameters, which means it can be checked rather than trusted — and the check is worth doing, because the most common reason a figure here differs from your payslip is not an error on either side. Four things account for nearly all of it.
A tax code that is not the standard one changes your allowance, and codes carrying an adjustment from an earlier year are common. A benefit in kind — a company car, private medical cover — is taxed through the code and does not appear as pay. A workplace pension deducted before tax reduces taxable pay, so your gross and your taxable figure are not the same number. And National Insurance is charged per pay period rather than annually, which is why a month containing a bonus takes proportionally more than the annual figures here imply, and why the year-end total still reconciles.
If none of those explains the gap, it may be an error on this side, and that is worth an email to corrections@taxwedge.com. Corrections are published with a date at /changes/ whether or not anyone else would have noticed.
Questions people actually ask
Is salary sacrifice better than a normal pension contribution?
For the same money into the pension, yes — because it saves National Insurance as well as income tax. At £50,000, sacrificing £5,000 costs £3,600 of take-home. A personal contribution of £5,000 would cost more, because the NI was already paid.
How much can I salary sacrifice?
Down to the National Minimum Wage for your hours, and within the pension annual allowance, which is £60,000 for most people and tapers for high earners. Your scheme will enforce the first; exceeding the second creates a tax charge.
Does salary sacrifice affect my mortgage application?
It can. Lenders assess your contractual salary, which is genuinely lower after sacrifice. Some lenders will add the pension contribution back; many will not. If a mortgage application is close, it is worth checking before increasing a sacrifice.