How 20% translates to £ per year
| Salary | 20% contribution | Monthly | Employer 3% match | Total in pension |
|---|---|---|---|---|
| £30,000 | £6,000 | £500 | £900 | £6,900 |
| £40,000 | £8,000 | £666 | £1,200 | £9,200 |
| £50,000 | £10,000 | £833 | £1,500 | £11,500 |
| £60,000 | £12,000 | £1,000 | £1,800 | £13,800 |
| £75,000 | £15,000 | £1,250 | £2,250 | £17,250 |
| £100,000 | £20,000 | £1,666 | £3,000 | £23,000 |
(Employer match assumed at UK auto-enrolment minimum 3%; many employers offer more.)
Real cost per £1 into pension at 20%
The stated 20% doesn't cost 20% 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 20% via salary sacrifice: - Gross contribution: £10,000/year - Take-home reduction: ~£7,200/year - Effective cost per £1 to pension: ~72p
For a £75,000 earner (higher-rate) contributing 20% via salary sacrifice: - Gross contribution: £15,000/year - Take-home reduction: ~£8,700/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 20% makes sense
This is aggressive — appropriate mostly for high earners (£75k+) who want to catch up on pension savings, cross the £100k taper safely, or maximise the annual allowance. Requires strong existing budget headroom.
When 20% 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 20%
For a £50,000 earner at 20%:
| Method | Take-home reduction | Effective cost per £1 to pension |
|---|---|---|
| Salary sacrifice | £7,200 | 72p |
| Net pay arrangement | £8,000 | 80p |
| Relief at source (basic rate only) | £8,000 | 80p |
| Relief at source + higher-rate claim via SA | £8,000 | 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 20% 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 — 20% specifics
See below — five questions common to this contribution level.
In short
A 20% 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 £10,000/year into pension, and £15,000 at £75,000. Sensible whenever you're already capturing employer match + haven't exceeded the £60,000 annual allowance.