Calculator inputs
5 inputs:
- Annual gross salary
- Pension contribution %
- Contribution method — salary sacrifice / net pay / relief at source
- Region — rUK or Scotland
- Tax year
Outputs
- Net pension contribution — what reaches your pension (annual + monthly)
- Side-by-side breakdown — without contribution vs with contribution
- Tax relief saved — the saving from your specific contribution + method
- Cost per £100 to pension — take-home cost to put £100 in pension
The 3 contribution methods compared
| Method | Income Tax relief | NI relief | Best for |
|---|---|---|---|
| Salary sacrifice | All bands automatic | Yes | Most workers — biggest saving |
| Net pay arrangement | All bands automatic | No | Many large employer schemes |
| Relief at source | Basic auto; higher via SA | No | Personal pensions, some workplace |
The NI saving is the differentiator. For basic-rate workers (8% NI), sacrifice saves 28% per £100 vs 20% for the other two methods. For higher-rate workers above the upper limit (2% NI), the gap narrows but sacrifice still wins.
Per-£100 cost by band
The most actionable output — what £100 in pension costs in take-home.
| Band | Salary sacrifice | Net pay | Relief at source |
|---|---|---|---|
| Under £12,570 | £92 (NI only) | £100 | £100 |
| Basic (£12,571–£50,270) | £72 | £80 | £80 (with SA for HR) |
| Higher (£50,271–£100k) | £58 | £60 | £60 + auto |
| Allowance taper (£100k–£125,140) | £38 | £40 | £40 + auto |
| Additional (£125,140+) | £53 | £55 | £55 + auto |
The differences are 2-8 percentage points depending on band — meaningful over a career.
Worked example — basic-rate salary sacrifice
£35,000 salary, 5% salary sacrifice into pension:
- Annual pension contribution: £1,750
- Without sacrifice: net annual ~£28,720
- With sacrifice: net annual ~£27,460
- Take-home reduction: £1,260
- Tax + NI relief saved: £490
- Cost per £100 to pension: £72
Worked example — basic-rate net pay
Same salary, same %, but via net-pay arrangement (no NI saving):
- Annual pension contribution: £1,750
- Without contribution: net annual ~£28,720
- With contribution: net annual ~£27,320
- Take-home reduction: £1,400
- Income Tax relief saved: £350
- Cost per £100 to pension: £80
For this worker, sacrifice saves £140/year compared to net pay — small but meaningful over a career.
Worked example — higher-rate £80k earner
£80,000 salary, 8% pension contribution. Comparing all 3 methods:
Salary sacrifice (£6,400): - Pension: £6,400 - Take-home drop: £3,712 - Tax + NI saved: £2,688 - Cost per £100: £58
Net pay (£6,400): - Pension: £6,400 - Take-home drop: £3,968 - Income Tax saved: £2,432 (no NI) - Cost per £100: £62
Relief at source (£6,400): - Personal contribution: £5,120 (you pay this from net pay) - Government adds: £1,280 (basic-rate top-up) - Additional via SA: £1,280 (higher-rate claim, returned to you) - Net cost: £3,840 - Cost per £100: £60
Higher-rate earners get similar outcomes from sacrifice vs Self Assessment claim. The Self Assessment route is more cash-flow friction (you wait for the refund) but ends at similar effective cost.
Important: many higher-rate workers don't claim their SA top-up — leaving thousands unrecovered. The pension impact calculator's relief-at-source figure assumes you DO claim.
Auto-enrolment baseline
UK auto-enrolment minimum: - 8% total (5% you + 3% employer) - Of qualifying earnings (£6,240–£50,270 in 2026/27)
So an auto-enrolled employee on £35,000: - Your 5% × (£35,000 − £6,240) = £1,438/year - Employer 3% × £28,760 = £863/year - Combined: ~£2,300/year into pension
For most workers, opting up to higher contribution % is value-positive — particularly if employer match scales (some schemes match up to 8% or 10%).
The annual allowance
£60,000 standard for 2026/27. Tapered to £10,000 if income exceeds £260,000.
Above the allowance, contributions face an "annual allowance charge" — extra tax. The calculator assumes you're within the allowance; high earners need to confirm separately.
Carry-forward of unused allowance from previous 3 tax years is permitted — useful for one-off large contributions.
Practical checklist
- Identify your contribution method in your scheme paperwork
- Use the calculator to see per-£100 cost at your salary
- Compare bands if you're near a band transition (e.g. £50k basic→higher)
- For higher-rate workers: confirm you're claiming Self Assessment relief if not on sacrifice
- For £100k+ workers: pension sacrifice is exceptionally tax-efficient via the 60% taper avoidance
In short
The pension impact calculator shows take-home impact, tax relief, and per-£100 cost for any contribution percentage. Salary sacrifice always wins on tax efficiency (saves NI on top of Income Tax). For £100k+ earners, sacrifice saves up to £62 of every £100 contributed. Use the salary sacrifice calculator for the tax-saving figure specifically; this calculator for the take-home picture.