The £100k trap: between £100,000 and £125,140 your Personal Allowance is withdrawn £1 for every £2 earned — an effective 60% marginal rate. Gift Aid donations reduce your adjusted net income, so they can restore the allowance on top of the normal 40% reclaim.

Allowance before

£5,070

of £12,570 available

Allowance after

£8,195

£3,125 restored

Effective relief

50%

£2,500 total on £5,000

Gift Aid grossed up (charity gets)
£6,250
Adjusted net income
£108,750
Your 40% reclaim (Self Assessment)
£1,250
Allowance-restoration saving
£1,250
Net cost of your donation
£2,500
Optimiser: to restore your full Personal Allowance, donate £12,000 (£15,000 grossed up) — bringing adjusted income back to £100,000. You’re currently £7,000 short of the full restoration.

Estimates only, not tax advice — 2025/26 UK rates (England & Wales). Scottish bands differ; pension contributions also reduce adjusted net income. Calculator by CharityCompare — free to use and embed.