How 40% translates to £ per year
| Salary | 40% contribution | Monthly | Employer 3% match | Total in pension |
|---|---|---|---|---|
| £30,000 | £12,000 | £1,000 | £900 | £12,900 |
| £40,000 | £16,000 | £1,333 | £1,200 | £17,200 |
| £50,000 | £20,000 | £1,666 | £1,500 | £21,500 |
| £60,000 | £24,000 | £2,000 | £1,800 | £25,800 |
| £75,000 | £30,000 | £2,500 | £2,250 | £32,250 |
| £100,000 | £40,000 | £3,333 | £3,000 | £43,000 |
(Employer match assumed at UK auto-enrolment minimum 3%; many employers offer more.)
Real cost per £1 into pension at 40%
The stated 40% doesn't cost 40% of take-home — tax + NI relief reduces the real cost. At standard workplace scheme + basic rate the effective cost per £1 into pension is about 72p; at higher rate 58p; in the £100k taper band just 38p.
For a £50,000 earner contributing 40% via salary sacrifice: - Gross contribution: £20,000/year - Take-home reduction: ~£14,400/year - Effective cost per £1 to pension: ~72p
For a £75,000 earner (higher-rate) contributing 40% via salary sacrifice: - Gross contribution: £30,000/year - Take-home reduction: ~£17,400/year - Effective cost per £1 to pension: ~58p
Above £100,000 the effective cost drops sharply as the personal allowance taper is neutralised by pension sacrifice — down to about 38p per £1 in the taper band. This is why high earners who cross £100k routinely sacrifice heavily.
When 40% makes sense
This is exceptional — only sensible for very high earners with strong existing savings, or those specifically catching up in the final decade before retirement. Above the £60,000 annual allowance a tax charge applies.
When 40% doesn't make sense
- If it takes you below National Minimum Wage (salary sacrifice can't legally reduce below NMW)
- If it takes you below auto-enrolment triggers and you lose employer match
- If short-term debt (credit-card, etc.) at 20%+ APR is not yet cleared — service that first
- If you're already above the £60,000 annual allowance (unless carry-forward is available)
Salary sacrifice vs net pay vs relief at source at 40%
For a £50,000 earner at 40%:
| Method | Take-home reduction | Effective cost per £1 to pension |
|---|---|---|
| Salary sacrifice | £14,400 | 72p |
| Net pay arrangement | £16,000 | 80p |
| Relief at source (basic rate only) | £16,000 | 80p |
| Relief at source + higher-rate claim via SA | £16,000 | 58-80p depending on band |
Salary sacrifice wins because it saves both Income Tax + NI. Relief at source captures basic rate only; higher-rate has to be claimed via Self Assessment.
Impact by tax band
At 40% contribution and salary sacrifice:
| Band | £1 into pension costs |
|---|---|
| Under £12,570 (personal allowance) | 92p (NI only) |
| Basic rate (£12,571-£50,270) | 72p |
| Higher rate (£50,271-£100k) | 58p |
| £100k personal allowance taper | 38p |
| Additional rate (£125,140+) | 53p |
Above £100k pension sacrifice is exceptionally tax-efficient.
FAQ — 40% specifics
See below — five questions common to this contribution level.
In short
A 40% UK pension contribution costs 72p per £1 for basic-rate workers, 58p for higher-rate workers, and just 38p between £100,000 and £125,140. On a £50,000 salary that's £20,000/year into pension, and £30,000 at £75,000. Sensible whenever you're already capturing employer match + haven't exceeded the £60,000 annual allowance.