The one-paragraph version
Salary sacrifice is a formal agreement between you and your employer to reduce your gross salary by a chosen amount, with the employer paying that amount directly into your pension instead. Because the redirected slice never reaches you as pay, you don't pay income tax or National Insurance on it, and your employer saves their 15% slice of NI too. For most UK employees with access to it, it beats every other way of contributing to a pension — by 8% for basic-rate taxpayers, much more for higher-rate, and dramatically more for anyone caught by the £100k Personal Allowance taper.
Salary Sacrifice Pension Calculator UK
Models income tax, NI (8%/2%), employer NI rebate, student loans, and Scottish bands. Live worked example. Free, no signup.
Run the calculator →What we're solving for
There are three ways to put money into a UK personal or workplace pension. They produce the same legal pension contribution, but they cost you different amounts of net pay and unlock different amounts of tax relief.
- Relief at source (RAS). The default for personal pensions and most workplace pensions. You contribute from your net pay. The provider claims 20% basic-rate relief from HMRC and adds it to your pot — so £80 from you becomes £100 in the pension. Higher-rate taxpayers have to claim the extra 20% (or 25% for additional rate) back from HMRC via Self Assessment. No NI saving.
- Net pay arrangement. Common in larger workplace schemes. The contribution comes out of your gross pay before income tax is calculated, so basic, higher and additional rates of relief are all applied automatically. Still no NI saving. No Self Assessment needed for the basic-rate slice.
- Salary sacrifice. You formally reduce your gross salary by the contribution amount. Because that slice of pay never legally exists, you don't pay income tax or employee NI on it, and your employer saves the 15% employer NI too. Some employers pass back some or all of that 15% as additional pension contribution.
The maths below quantifies how much extra salary sacrifice puts in your pension or your pocket compared to a default 5% RAS workplace contribution. The same logic applies to any contribution percentage.
The 2026/27 tax landscape
To run the maths we need the current bands and thresholds. These are the figures the calculator uses; verify against HMRC and gov.scot before relying on them for a real decision.
Income tax — rest of UK (rUK)
| Band | Range | Rate |
|---|---|---|
| Personal Allowance | £0 – £12,570 | 0% |
| Basic rate | £12,571 – £50,270 | 20% |
| Higher rate | £50,271 – £125,140 | 40% |
| Additional rate | £125,141 + | 45% |
PA tapers between £100,000 and £125,140 — you lose £1 of allowance for every £2 of income above £100k, creating the famous 60% effective marginal rate.
Income tax — Scotland
| Band | Range | Rate |
|---|---|---|
| Personal Allowance | £0 – £12,570 | 0% |
| Starter | £12,571 – £15,397 | 19% |
| Basic | £15,398 – £27,491 | 20% |
| Intermediate | £27,492 – £43,662 | 21% |
| Higher | £43,663 – £75,000 | 42% |
| Advanced | £75,001 – £125,140 | 45% |
| Top | £125,141 + | 48% |
Income tax is devolved in Scotland; NI and the Personal Allowance taper are not. So a Scottish higher-rate taxpayer pays 42% income tax + 2% NI = 44% on the relevant slice, vs. 40% + 2% = 42% in rUK. Salary sacrifice saves all of that.
National Insurance
| Type | Threshold | Rate |
|---|---|---|
| Employee — main rate | £12,570 – £50,270 | 8% |
| Employee — upper rate | Above £50,270 | 2% |
| Employer (Secondary) | Above £5,000 | 15% |
Employer NI changed materially in April 2025: rate up from 13.8% to 15%, Secondary threshold down from £9,100 to £5,000. This makes the employer's NI saving on salary sacrifice meaningfully larger than before — and worth asking HR whether they pass any of it on.
Student loan thresholds
| Plan | Threshold | Rate |
|---|---|---|
| Plan 1 | £26,065 | 9% |
| Plan 2 | £28,470 | 9% |
| Plan 4 (Scotland-funded) | £32,745 | 9% |
| Plan 5 (started after Aug 2023) | £25,000 | 9% |
| Postgraduate Loan | £21,000 | 6% |
Salary sacrifice reduces the salary used to calculate student loan repayments — so it cuts your loan deduction too. For a Plan 2 graduate sacrificing £4,000 on a £40,000 salary, that's £360/year less leaving as loan repayments. Over 30 years (the typical write-off period), that's £10,800 of cash flow improved — at the cost of a slightly larger written-off balance, which most graduates never repay in full anyway.
Worked example 1 — basic-rate taxpayer on £40,000
Sarah earns £40,000, currently contributes 5% via her workplace RAS scheme, has no student loan, lives in England. She's considering switching to an 8% salary sacrifice instead.
Before — 5% RAS contribution
| Gross salary | £40,000 |
| Income tax (20% on £27,430) | −£5,486 |
| Employee NI (8% on £27,430) | −£2,194 |
| Pension contribution from net pay (5%) | −£2,000 |
| Take-home | £30,320 |
| Pension contribution + basic-rate top-up | £2,500 |
After — 8% salary sacrifice
| Gross salary | £40,000 |
| Less salary sacrifice (8%) | −£3,200 |
| Taxable salary | £36,800 |
| Income tax (20% on £24,230) | −£4,846 |
| Employee NI (8% on £24,230) | −£1,938 |
| Take-home | £30,016 |
| Pension contribution (sacrifice) | £3,200 |
Result. Sarah's take-home drops by £304 but her pension gets £700 more. Net benefit: +£396 a year. If her employer also passes back the 15% employer NI saving on the £3,200 sacrifice (£480), the total benefit jumps to +£876 a year.
Worked example 2 — higher-rate taxpayer on £80,000
Tom earns £80,000, currently puts 5% into RAS (and claims back the higher-rate slice via Self Assessment), has no student loan, lives in England. He's switching to 10% salary sacrifice.
Before — 5% RAS, with Self Assessment claim
| Gross salary | £80,000 |
| Income tax (20% basic + 40% higher) | −£19,432 |
| Employee NI (8% to £50,270, then 2%) | −£3,611 |
| Pension contribution from net pay (5%) | −£4,000 |
| Plus higher-rate relief reclaim via SA | +£1,000 |
| Take-home (after SA reclaim) | £53,957 |
| Pension contribution + 20% provider top-up | £5,000 |
After — 10% salary sacrifice
| Gross salary | £80,000 |
| Less salary sacrifice (10%) | −£8,000 |
| Taxable salary | £72,000 |
| Income tax (20% basic + 40% higher on £21,730) | −£16,232 |
| Employee NI (8% to £50,270, then 2% on £21,730) | −£3,451 |
| Take-home | £52,317 |
| Pension contribution (sacrifice) | £8,000 |
Result. Tom's take-home drops £1,640 but his pension gains £3,000. Net benefit: +£1,360 a year — and that's without any employer NI rebate. He's also avoided the Self Assessment paperwork. If his employer rebates the £1,200 employer NI saving on the sacrifice, the total benefit hits +£2,560 a year.
The £100k tax trap — where sacrifice is most powerful
This is the single most important point in the whole article.
Between £100,000 and £125,140 of taxable income, the UK Personal Allowance tapers away. You lose £1 of the £12,570 allowance for every £2 you earn over £100k. By £125,140 the PA is gone entirely.
The maths: an extra £1 of income above £100k costs you 40p in income tax directly, plus 20p in lost PA relief (the PA is worth 40% × that lost £0.50 = £0.20). That's a 60% effective marginal rate. Adding 2% NI takes it to 62%.
This is the highest marginal rate the UK tax system applies to any band — higher than the 47% additional rate above £125,140. It's a flat-out absurdity that the band most people don't even know about is taxed harder than the band labelled "additional".
Salary sacrifice into a pension is the cleanest possible way out. Every £1 you sacrifice in this band saves you 60p (or 62p with NI) of tax — and the full £1 lands in your pension. Effectively you're getting a £1 pension contribution for 38–40p of give-up. There is no other tax-efficiency play in the UK system that comes close.
Worked example 3 — £110,000 earner
Priya earns £110,000. Her Personal Allowance is currently tapered to £12,570 − (£10,000 / 2) = £7,570. She sacrifices £10,000 into her pension.
- Her taxable salary drops to £100,000. Full Personal Allowance restored (£12,570).
- Income tax saving: 40% × £10,000 = £4,000 direct.
- Plus the restored £5,000 of PA × 40% = £2,000 of income tax she was paying on the slice the PA now covers.
- Plus 2% NI on £10,000 = £200.
- Total saved: £6,200 on a £10,000 sacrifice = 62% effective relief.
Priya gave up roughly £3,800 of take-home and gained £10,000 in pension — a transfer worth £6,200, in one stroke. That's why the calculator flags this band specifically.
What we don't model — and where to be careful
Mortgage applications
Most UK lenders use your post-sacrifice salary for affordability. If your stated salary on payslips is £45,000 after sacrificing from £50,000, your maximum mortgage is normally calculated on £45k. Halifax, Nationwide and Barclays have all granted "gross-back-up" exceptions when you produce payslips proving the sacrifice — but it isn't guaranteed, and brokers report it's harder than it used to be. If a mortgage is coming up in the next 12 months, pause the sacrifice or run the application before starting.
Statutory pay and State Pension
State Pension qualifying years are credited if your "earnings" exceed the Lower Earnings Limit (£6,396/year in 2025/26). Statutory Sick Pay, Maternity Pay and other statutory payments are based on average weekly earnings above the LEL. Sacrifice that drops you below these thresholds eliminates the relevant credit. For anyone earning roughly £12k+ post-sacrifice, you're well clear.
Life cover and group income protection
Many UK workplace life cover schemes pay "4 × salary" on death. Check whether "salary" in your scheme means "reference salary" (the pre-sacrifice figure) or "post-sacrifice salary". Most modern schemes use reference salary, but older ones can be ambiguous. A quick HR query is worth doing.
Annual Allowance taper
If your "adjusted income" is above £260,000, the standard £60,000 Annual Allowance for pension contributions tapers down, reaching a minimum of £10,000. If you're at this income level, do not max out salary sacrifice without checking — exceeding the Annual Allowance triggers an Annual Allowance charge, which can be hefty.
Money Purchase Annual Allowance (MPAA)
If you've already taken taxable income from a defined-contribution pension (flexi-access drawdown or a small UFPLS), your annual contribution limit drops to £10,000 for life. This affects mostly people who took a small drawdown to fund a sabbatical or business venture, then went back to work.
What about the employer NI rebate?
The 15% employer NI on the sacrificed amount is a saving that legally belongs to the employer. A growing number of UK companies pass it on — sometimes 100%, sometimes 50%, sometimes via a flat uplift on the employer contribution. Examples we've seen in the wild:
- Full rebate. The full 15% employer NI saving goes straight into your pension on top of the sacrificed amount. Worth ~£480/year on an 8% sacrifice from £40k.
- Partial rebate. A common compromise. Some employers pass back 50% — keeping half the saving for themselves, half for you.
- No rebate. The employer keeps the entire NI saving. Still the most common arrangement, but ask — many companies will pass it on if asked, particularly tech and finance.
The single most useful question to ask HR at a new job — or at your next review — is: "Do you pass on the employer NI saving when I salary sacrifice?" The answer is worth several hundred pounds a year for the rest of your career.
How the calculator's maths is wired
For each scenario the engine does the same five-step calculation:
- Compute the taxable salary: gross salary minus any salary sacrifice.
- Compute the effective Personal Allowance: £12,570, tapered if taxable salary lands between £100k and £125,140.
- Compute income tax band by band, applying rUK or Scottish rates depending on the country selector.
- Compute employee NI: 8% from the Primary Threshold to the Upper Earnings Limit, 2% above.
- Compute the student loan deduction, if any: 9% (or 6% for postgrad) on the slice above the relevant plan threshold.
The "before" pension contribution is treated as relief-at-source: you contribute from net pay, the provider claims 20% basic-rate top-up. Higher-rate taxpayers normally reclaim the additional 20% via Self Assessment — the calculator's headline number doesn't model that reclaim (it would only reduce the apparent benefit of switching, never reverse it). The worked example in this guide above does include it explicitly to make Tom's "before" picture realistic.
The "after" pension contribution is the sacrifice amount, plus the employer NI rebate if you've ticked the toggle. The rebate is calculated as the difference between employer NI on the full salary and employer NI on the reduced salary, both using the 2026/27 Secondary threshold of £5,000 and the 15% rate.
What the headline number means
The "annual benefit" on the result panel adds two things together:
- The change in take-home pay (usually negative — sacrificing more means a bit less in your pocket each month).
- The change in total pension contribution (always positive when sacrificing more, including any employer NI rebate).
It's the net transfer from "money in your hand right now" to "money in your pension". A positive number means the move is unambiguously better in total wealth terms — sacrifice gives you more pension than the take-home you give up costs. For nearly every UK employee with access to sacrifice, this number is positive at every sensible contribution level.
Sources and further reading
- HMRC: Income Tax rates and Personal Allowance
- HMRC: National Insurance rates and categories
- HMRC: Tax credits rates and thresholds (annual update)
- HMRC: Student loan repayment thresholds
- gov.scot: Scottish Income Tax 2025/26 factsheet
- HMRC: Tax on your private pension contributions
- HMRC: Annual Allowance and tapered Annual Allowance
Run your own numbers
The full calculator: live tax + NI + student loan + Scottish bands, all the worked steps, no signup.
Open the calculator →This is general information, not financial or tax advice. Rates change, and personal circumstances vary. For decisions involving bonus sacrifice at high salaries, defined benefit pension accrual, or the Annual Allowance taper, speak to a regulated UK financial adviser or accountant.