Salary sacrifice calculator (UK)
See how much more take-home pay salary sacrifice leaves you with than a relief-at-source pension contribution for the same amount in your pot — the National Insurance saving is the difference.
Salary sacrifice puts this much more in your pocket
£180
Compared with a relief-at-source contribution reaching the same £2,250 in your pension — including any higher-rate relief you'd have to separately reclaim to get there.
Salary sacrifice
Take-home pay
£34,300
Relief at source
Take-home pay
£34,120
Why sacrifice wins
Your NI saved
£180
Your employer also saves £338 in Employer's National Insurance on the sacrificed amount — some employers pass some or all of this back into your pension as a boost. It's worth asking payroll or HR whether yours does.
Estimates use simplified 2026/27 UK Income Tax, National Insurance, and student loan rules. Your employer must keep your contractual pay at or above the National Minimum Wage after any sacrifice — if the sacrifice shown here would breach that, your employer can't offer it in full. Not financial advice.
How salary sacrifice works
With salary sacrifice, you agree to a lower contractual salary in exchange for your employer paying the difference straight into your pension. Because the sacrificed amount never counts as your salary in the first place, it's never subject to Income Tax or National Insurance — unlike a relief-at-source contribution, which comes out of pay that's already been taxed and had NI deducted, with only the tax (not the NI) refunded, and only automatically up to the basic rate.
Because your reported salary is lower, sacrifice can also reduce a student loan repayment (which is based on income above a threshold) and, for income between £100,000 and £125,140, restore some of the personal allowance that's otherwise withdrawn — the same "60% trap" relief a relief-at-source contribution gets too, just without the separate claim.
The main downside: a lower contractual salary can affect things calculated from it, like mortgage affordability assessments, statutory maternity/paternity pay, and some means-tested benefits — worth checking before sacrificing a large amount.