UK Gift Aid Calculator: Top-Up a Charity Claims on Your Donation
Work out UK Gift Aid — the top-up a charity can reclaim from HMRC on your donation — and the gross value of your gift, so a £100 donation is worth £125 to the charity at no extra cost to you.
Adjust the inputs and select Calculate for a full breakdown.
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Gift Aid top-up | Gross gift to charity |
|---|---|---|
| 25% of £100 (£25 top-up) | $25.00 | $125.00 |
| 25% of £50 | $12.50 | $62.50 |
| 25% of £500 | $125.00 | $625.00 |
| 25% of £1,000 | $250.00 | $1,250.00 |
How This Calculator Works
Enter your donation and the Gift Aid reclaim rate (25%). The calculator shows the top-up the charity reclaims and the gross gift (your donation plus the top-up). Gift Aid lets charities reclaim the basic-rate tax you already paid on the money you donate, boosting your gift by 25% — provided you're a UK taxpayer and have made a Gift Aid declaration.
The Formula
Percentage Add-On
Rate is the tax or tip percentage applied to the amount
Worked Example
On a £100 donation with Gift Aid, the charity reclaims £25, making your gift worth £125. Gift Aid works because your donation is treated as made from taxed income: the charity reclaims the 20% basic-rate tax on the grossed-up amount. Since £125 grossed up at 20% tax leaves £100, the reclaim is £25 — a 25% boost on your cash donation. You must have paid at least £25 of UK Income or Capital Gains Tax in that year for HMRC to honour the reclaim.
Key Insight
Gift Aid is one of the simplest ways to increase the value of UK charitable giving, and a couple of mechanics explain the figures. The 25% boost comes from grossing up: HMRC treats your donation as the after-basic-rate-tax remainder of a larger gross gift. At a 20% basic rate, £100 is what's left of £125 after tax, so the charity reclaims the £25 of 'tax' — which is why the top-up is 25% of your cash donation, not 20%. The conditions: you must be a UK taxpayer who has paid (in Income Tax or Capital Gains Tax) at least as much as all the charities will reclaim on your donations that year, and you must make a Gift Aid declaration (a one-off or enduring statement) to each charity. A separate, valuable layer this calculator doesn't compute: if you're a higher-rate (40%) or additional-rate (45%) taxpayer, you can personally claim back the difference between your rate and the basic rate on the gross donation through your Self Assessment return — for a £100 donation (£125 gross), a 40% taxpayer reclaims £25, so the gift costs them just £75 net while the charity still gets £125. Points to watch: Gift Aid can only be claimed on genuine gifts of money (not on the value of goods or services received in return, with limited benefit allowances), and donating more than you've paid in tax can leave you owing HMRC the shortfall, so don't tick the Gift Aid box if you're a non-taxpayer. This calculator shows the charity's 25% top-up and the gross gift; higher-rate donors should also remember the extra personal relief they can reclaim.
Frequently Asked Questions
How is Gift Aid calculated?
The charity reclaims 25% of your cash donation. On £100, that's a £25 top-up, making the gross gift £125. The 25% comes from grossing up: £125 less 20% basic-rate tax is £100, so the £25 of tax is what the charity reclaims from HMRC.
Why is the top-up 25% and not 20%?
Because the reclaim is 20% of the grossed-up gift, not 20% of your donation. Your £100 is treated as the after-tax remainder of a £125 gross gift; 20% of £125 is £25. Expressed against your actual £100 donation, that £25 is a 25% boost.
Who can use Gift Aid?
UK taxpayers who have paid at least as much Income or Capital Gains Tax in the year as all the charities will reclaim on their donations, and who make a Gift Aid declaration to each charity. If you don't pay enough tax, you shouldn't claim Gift Aid, as HMRC could ask you for the shortfall.
Can higher-rate taxpayers get extra relief?
Yes. If you pay 40% or 45% tax, you can personally reclaim the difference between your rate and the basic rate on the gross donation via Self Assessment. For a £100 donation (£125 gross), a 40% taxpayer reclaims £25 — so the gift costs them £75 while the charity still receives £125.
What donations qualify for Gift Aid?
Genuine gifts of money to a UK-registered charity or CASC. It can't be claimed on the value of goods or services you receive in return (beyond small benefit allowances), on donations of goods directly, or by non-taxpayers. A valid Gift Aid declaration must be in place for the charity to claim.
Related Calculators
Methodology & Review
The Gift Aid top-up is the reclaim rate applied to the cash donation; the total is the donation plus the top-up — the gross value of the gift to the charity. The 25% rate reflects basic-rate tax being reclaimed on the grossed-up donation. It does not compute the extra higher-rate relief a higher-rate donor can claim back personally.
Written by Ugo Candido · Last updated May 22, 2026.