“Salary sacrifice” sounds like you're giving something up for nothing. You're not. It's simply a different way of paying for something you were probably going to pay for anyway, most often a pension, in a way that costs you less tax. Here's what it actually means, in plain English rather than payroll jargon.
What is salary sacrifice, in plain English?
You agree with your employer to permanently reduce your contractual salary, and in exchange your employer gives you a non-cash benefit of equivalent (or greater) value, most commonly a pension contribution. Because your contractual salary is genuinely lower, you're taxed on the lower figure, not the amount you would have earned without the arrangement.
A simple, illustrative example
Say your salary is £30,000 a year and you agree to sacrifice £1,800 a year (£150 a month) into your pension. Your contractual salary drops to £28,200. HMRC and your employer's payroll system now calculate your Income Tax and National Insurance on £28,200, not £30,000. The £1,800 goes straight into your pension pot as an employer contribution, without ever being paid to you, taxed, or having National Insurance deducted from it.
The exact saving depends on your tax band, so this is illustrative rather than a substitute for running your own numbers.
Why does it actually save money?
Two separate savings stack on top of each other. First, Income Tax: you don't pay it on money you never officially earned. Second, and often overlooked, employee National Insurance: because your cash pay is lower, you also pay less National Insurance on it. Paying into a pension from your take-home pay instead only gets you the Income Tax relief back, usually claimed automatically at the basic rate; it doesn't touch your National Insurance bill at all. That's the main reason salary sacrifice tends to be more valuable, pound for pound, than paying into a pension after you've already been taxed.
What can you actually sacrifice salary for?
Pension contributions are by far the most common, and the one where the tax advantage is most reliable. A smaller set of other benefits can also be arranged this way, including Cycle to Work schemes, some employer-arranged pensions advice, workplace nurseries, and ultra-low-emission cars. Since 2017, rules known as “optional remuneration arrangements” mean most other benefits lost their tax advantage under salary sacrifice, so it's worth checking that whatever your employer is offering is still on the exempt list before assuming it will save you anything.
Things worth thinking through before you sign up
- Your contractual salary genuinely falls, so mortgage lenders, some means-tested benefit calculations, and statutory redundancy pay may all use the lower figure, not your “real” earning capacity.
- By law, an arrangement can't reduce your cash pay below the National Minimum Wage or National Living Wage, so employers will usually cap how much you can sacrifice if your salary is closer to that level.
- It requires a formal change to your employment contract, so it isn't something you can casually turn on and off mid-month.
- For pension sacrifice specifically, your total contribution still counts towards your pension Annual Allowance, currently the standard allowance for most people, so very high sacrifices are worth checking against that limit.
If your employer has offered you a scheme, or you're weighing up whether to start one, the salary sacrifice calculator runs the real numbers for your own salary using this year's actual tax bands, so you can see the effect on your take-home pay before deciding.