Gift Aid Calculator
Gift Aid lets a UK charity reclaim the basic-rate Income Tax you've already paid on the money you donate, directly from HMRC, at no extra cost to you. When you tick the Gift Aid declaration box, the charity treats your donation as if it had been paid out of your income before basic-rate tax was deducted, and claims that 20% back.
The maths works out as a 25% uplift: because the donation you hand over is treated as the "after-tax" 80% of a larger gross amount, dividing your donation by 0.8 (equivalently, multiplying by 1.25) gives the gross value the charity actually receives. A £100 donation becomes £125 for the charity — an extra £25 that costs you nothing beyond ticking a box, since it's simply the tax you'd already paid on that money being redirected to the charity instead of staying with HMRC.
The 25% charity uplift is the same for every donor regardless of their own tax rate, but higher-rate (40%) and additional-rate (45%) taxpayers can claim back further relief for themselves, on top of what the charity receives. HMRC does this by extending your basic-rate band by the gross (grossed-up) value of your donation — effectively meaning more of your income is taxed at 20% instead of 40% or 45%, which produces exactly the same effect as reclaiming the difference between your rate and the basic rate on the donation.
In practice, this means a higher-rate taxpayer can claim back 20 percentage points (40% minus the 20% already claimed by the charity) of the grossed-up donation value, and an additional-rate taxpayer can claim back 25 percentage points (45% minus 20%). This extra relief goes to you personally, not the charity, and must be actively claimed — either through the "Gift Aid" section of a Self Assessment tax return, or by phoning HMRC to have your tax code adjusted if you don't otherwise need to file a return.
To use Gift Aid, you must be a UK taxpayer and have paid enough Income Tax or Capital Gains Tax during the tax year to cover the amount the charity (and, if applicable, you) will reclaim. This condition catches people out more often than you'd expect — a non-taxpayer (someone earning below the Personal Allowance, or a pensioner with only a small income) who ticks the Gift Aid box on a donation without checking their own tax position can end up owing HMRC the shortfall directly, since the charity's claim still goes through even if the underlying tax wasn't actually paid.
The declaration itself is simple — a one-off tick-box or statement confirming you want Gift Aid applied, which many charities now let you make once to cover all future donations rather than repeating it every time. It's worth periodically reviewing which charities hold an active Gift Aid declaration from you, particularly after a significant change in income (retirement, redundancy, a big pay cut) that might take you below the tax-paying threshold.
Consider a higher-rate (40%) taxpayer donating £500 to a charity with Gift Aid ticked. The charity's gross received amount is £500 ÷ 0.8 = £625 — an extra £125 compared with the £500 actually handed over, funded entirely by HMRC reclaiming the basic-rate tax already paid on that money.
The donor can then separately claim back the higher-rate top-up on their own Self Assessment return: 20 percentage points (40% higher rate minus the 20% basic rate already reclaimed by the charity) of the £625 gross value, which is £625 × 20% = £125. That £125 comes back to the donor personally, typically as a reduction in their overall tax bill or a repayment, rather than going to the charity.
Adding it up: the charity receives £625, the donor's own tax bill falls by £125, meaning the donor's real, final out-of-pocket cost of generating £625 for the charity is £500 − £125 = £375 — considerably less than the £625 the charity actually receives, and a clear illustration of why higher-rate taxpayers who give regularly to charity but don't actively claim this relief are quietly leaving money on the table every year.
Because Gift Aid works by extending your basic-rate band rather than simply cutting a cheque, it can interact with several other parts of the tax system in ways that aren't obvious from the headline 20%/25% figures. If your income sits close to £100,000, Gift Aid donations reduce your adjusted net income, which can help restore some of the tapered Personal Allowance that would otherwise be lost above that threshold, or reduce a High Income Child Benefit Charge if your (or your partner's) income is close to the relevant threshold.
This means the real value of a Gift Aid donation for someone in one of these income bands can be considerably higher than the simple higher-rate calculation suggests, since the donation is simultaneously reducing multiple separate tax charges at once. Anyone regularly donating significant sums and sitting near £100,000, or near the Child Benefit charge thresholds, should consider getting a fuller calculation done (an accountant, or HMRC's own guidance) rather than relying solely on the basic Gift Aid relief figure.
Gift Aid isn't the only way to give tax-efficiently. Payroll Giving (also called Give As You Earn) lets an employee donate directly from gross salary before tax is deducted, giving instant relief at their full marginal rate through payroll rather than requiring a Self Assessment claim afterwards — useful for higher and additional-rate taxpayers who'd otherwise need to remember to claim the extra relief themselves. The two schemes are mutually exclusive for the same donation: money given through payroll giving hasn't had Gift Aid applied to it separately, since it was never taxed in the first place.
Not everything you give to a charity qualifies for Gift Aid. Donations must be a genuine gift with no significant benefit received in return — buying a raffle ticket, paying for goods at a charity auction, or paying a membership fee that includes substantial benefits generally doesn't qualify, though there are specific, narrow exemptions (a small "thank you" gift below a set value threshold, for example, doesn't disqualify a donation). Sponsored events (a charity fun run, for instance) do typically qualify, provided the sponsor is a genuine UK taxpayer and completes a proper Gift Aid declaration, which is why sponsorship forms almost always include a Gift Aid tick-box and a declaration of taxpayer status.
Smaller charities also benefit from the Gift Aid Small Donations Scheme (GASDS), which lets them claim a Gift-Aid-style top-up on small cash and contactless donations (such as a collection bucket) up to a set annual limit, without needing an individual Gift Aid declaration for every donor — useful context if you're a charity trustee or treasurer rather than an individual donor, since it changes what paperwork is actually required for small, informal donations.