Salary Sacrifice Pension Calculator

Salary sacrifice reduces your gross contractual pay and your employer pays the sacrificed amount straight into your pension. Because the money arrives as an employer contribution, neither employee National Insurance, charged at 8% on earnings between £12,570 and £50,270, nor employer National Insurance at 15% is due on it. Relief at source only ever hands back income tax, so wherever National Insurance applies, sacrifice is the more efficient of the two routes. From 6 April 2029 the National Insurance saving is limited to the first £2,000 sacrificed each year, under the National Insurance Contributions (Employer Pensions Contributions) Act 2026, while the income tax relief carries on unchanged.

Take-home pay is what the comparison actually turns on. Paying £500 a month into a pension from a £40,000 salary under relief at source costs you £400, since the provider reclaims 20% basic-rate relief on top. Sacrifice the same £500 and your salary falls by £500, but £40 of employee National Insurance falls away with it, so net pay drops by only £360. That £40 a month is the whole of the difference, and it either reaches the pension or stays in your pocket.

Your employer saves as well, 15% of whatever is sacrificed, which comes to £75 on a £500 contribution. Larger employers also avoid the 0.5% Apprenticeship Levy on that slice of pay. Many schemes share part or all of the saving by adding it to your pension, so a £1,000 sacrifice can land as £1,150 where the full £150 is passed on. Arrangements like this are usually called NI passback, and it is worth asking HR whether yours operates one, since it costs the employer nothing beyond a little administration.

For a higher-rate taxpayer the arithmetic sharpens further. Under relief at source you pay in £80 of net income, HMRC adds £20, and the remaining 20% has to be claimed back through self-assessment. Sacrifice £100 of gross pay instead and take-home falls by £72 on the basic rate or £58 on the higher rate, with income tax and National Insurance both saved at the point of payment. That is 42% saved on the sacrificed slice, 40% income tax plus 2% National Insurance, against 40% under relief at source. Tick the Scottish taxpayer box to use Scotland's bands: on £50,000, sacrificing £5,000 saves £2,100 of income tax at 42% plus £400 of National Insurance.

Sacrifice also reduces the gross pay used for several other tests, and that is where it can bite. It cannot take you below the National Minimum Wage of £12.71 an hour for the hours you work. It feeds into the Statutory Maternity Pay calculation, into the earnings that count towards your State Pension, and into mortgage affordability assessments. Anyone heading for maternity leave should normally pause the sacrifice before the SMP reference period starts. The calculator warns when a sacrifice would push pay under the lower earnings limit of £6,708, and when pay falls below the minimum-wage level for a 37.5-hour week, which you should check against your real hours.

The strongest case of all sits between £100k and £125,140, where the effective marginal rate reaches 60% because 40% income tax is joined by the Personal Allowance taper worth another 20 points. Sacrificing that slice is close to the most tax-efficient move available in UK personal finance. Giving up £25,140 from an income of £125,140 costs £9,553.20 in take-home pay and puts the whole £25,140 into the pension, relief of 62% (60% income tax plus 2% National Insurance) before the employer's £3,771 National Insurance saving is counted. Through relief at source the same contribution costs £10,056. Plenty of high earners simply target an adjusted income just under £100k.