Salary sacrifice is one of the most valuable things an employee can do with their pay, and one of the least well explained. Your employer mentions it once during onboarding, the pension provider sends a leaflet, and the actual question you want answered goes unanswered: if I sacrifice a hundred pounds a month, what happens to my take-home pay?
PensionSacrifice exists to answer that one question properly.
What the calculator does
You enter your gross salary and the amount you want to sacrifice. The calculator works out your revised take-home pay, the National Insurance you and your employer both save, the tax relief you receive, and the total that actually lands in your pension. It shows the before and after side by side, because the useful insight is almost always the difference rather than either figure alone.
It handles the parts people trip over: the National Insurance saving that makes sacrifice more efficient than a standard personal contribution, the effect on higher and additional rate thresholds, and the point at which sacrificing further stops being worthwhile because you have crossed a band.
Where the figures come from
Income Tax bands, National Insurance thresholds and rates are taken from HMRC published rates for the current tax year. Scottish taxpayers are handled separately, because Scotland has set its own Income Tax bands since 2017 while National Insurance remains UK-wide. We review the figures when HMRC publishes changes, typically at each Budget and again before the start of the tax year in April.
Where a figure is an assumption rather than a published rate, we say so on the page rather than burying it.
Who publishes this site
PensionSacrifice is built and maintained by CJ Software Ltd, a UK software company that develops a small family of free, single-purpose calculators. We are a software business, not a firm of financial advisers, and we say so plainly because it matters when you decide how much weight to give a number on a screen.
The site is funded by advertising. Advertisers have no influence over the calculations, the guidance, or what we choose to write about.
What this tool is not
It is an estimate, not advice. It cannot see your full circumstances: other income, existing pension arrangements, the annual allowance, the tapered annual allowance if you are a high earner, or whether salary sacrifice would affect your entitlement to statutory payments, mortgage borrowing, or means-tested benefits. Those are real considerations and a calculator cannot weigh them for you.
For decisions that matter, speak to a regulated financial adviser or check the current guidance on GOV.UK. If you think a figure here is wrong, we would genuinely like to know, and corrections get priority over new features.