What this checker works out
Salary sacrifice means giving up part of your gross salary in exchange for a benefit — most commonly an employer pension contribution. Because the money never counts as pay, you do not pay income tax or National Insurance on it.
This checker takes the monthly amount you would sacrifice and your tax and National Insurance rates, and shows what that contribution actually costs you in take-home pay.
Salary sacrifice estimate
Before you decide
- Confirm your employer operates salary sacrifice. Not all do, and an ordinary pension contribution works differently and saves less.
- Select the tax band that applies to the portion being sacrificed, not your average rate.
- Check whether your employer passes on their own National Insurance saving. Some add it to your pension; many do not.
- Consider what a lower gross salary affects: mortgage borrowing, life cover based on salary, statutory maternity pay, and some state benefits.
An ordinary pension contribution gets income tax relief but not National Insurance relief. Salary sacrifice avoids both, because the money is never treated as your earnings. For a basic rate taxpayer that is an extra 8% saved on every pound.
How this calculator works
The saving is the tax and National Insurance you would otherwise have paid:
Tax saved = amount sacrificed × your income tax rate
NI saved = amount sacrificed × your National Insurance rate
Take-home cost = amount sacrificed − tax saved − NI savedThe full amount still goes into your pension. Only the cost to you falls, which is what makes salary sacrifice efficient rather than simply cheaper.
The checker does not model the employer National Insurance saving, employer matching or investment growth. Each of those improves the outcome further, so treat the figure as the conservative case.
Worked example: £100 a month into a pension
Using the default figures — £100 a month sacrificed, basic rate tax at 20% and National Insurance at 8%:
- Income tax saved: £100 × 20% = £20
- National Insurance saved: £100 × 8% = £8
- Cost to your take-home pay: £72
- Amount added to your pension: £100
£100 of pension for £72 of take-home pay is a 39% uplift before any employer contribution or investment growth. For a higher rate taxpayer sacrificing at 40% with 2% National Insurance, the same £100 costs £58 — a 72% uplift. The trade is that the money is locked away until pension access age, currently 55 and rising to 57.
Common mistakes
- Sacrificing below the National Minimum Wage. Salary sacrifice cannot reduce your pay below it, so employers will cap or refuse the arrangement.
- Overlooking the effect on borrowing. A lower gross salary can reduce what a mortgage lender will advance.
- Forgetting about salary-linked benefits. Death in service cover, statutory maternity pay and redundancy pay may be based on the reduced figure.
- Using an average tax rate rather than the marginal one. The saving applies at the rate on the top slice of your income.
- Assuming it can be reversed at will. Salary sacrifice is a contractual change and can usually only be altered at set points or on a life event.
Frequently asked questions
Is salary sacrifice always worth it for a pension?
Usually, if you can afford the reduction in take-home pay and you are comfortable with the money being inaccessible until pension age. It is one of the few arrangements that saves both income tax and National Insurance. The main reasons to hesitate are needing the income now, being close to the minimum wage floor, or planning a mortgage application in the near future.
Does it affect my State Pension?
It can, in principle, if the reduction takes your earnings below the level at which you build a qualifying year. For most people sacrificing a modest amount from a normal salary, earnings remain comfortably above that level and there is no effect. If you are a lower earner, check before committing.
What is the effect at £100,000 of income?
It can be substantial. The Personal Allowance is withdrawn gradually above £100,000, producing a marginal rate of around 60% in that band. Sacrificing salary to stay below the threshold is one of the more effective uses of the arrangement, and is worth taking advice on.
Can I use salary sacrifice for other benefits?
Yes — common schemes cover cycle to work, ultra-low emission cars, and additional annual leave. The tax treatment varies considerably by benefit, and the rules were tightened in recent years so that many benefits no longer receive the same advantage as pensions.
How does this affect a mortgage application?
Lenders assess your gross salary after sacrifice, which is lower. Some will add the pension contribution back when assessing affordability, but many will not. If you are applying for a mortgage soon, it is worth asking your lender before increasing a sacrifice arrangement.
Related tools
References
- GOV.UK — salary sacrifice rules, minimum wage interaction and affected benefits
- MoneyHelper — guidance on pension contributions, tax relief and salary sacrifice
- HM Revenue & Customs — the tax treatment of salary sacrifice arrangements
Sources are checked at publication and can change — how I choose and check references.