Gift Aid Calculator United Kingdom

Many UK donors never claim all the tax relief their giving earns. This calculator shows what the charity receives from your donation in 2026/27, how much of your own tax you can reclaim and what the gift costs you once both are counted. Enter the amount and your income to see all three figures.

The two halves of Gift Aid relief

Gift Aid splits the relief between the charity and the donor, and most people only see the first half.

Your donation is treated as made from income on which you have already paid basic rate tax. The charity reclaims that tax from HMRC, which is why £80 becomes £100 and £1,000 becomes £1,250. This happens automatically once you sign a declaration, costs you nothing and needs no paperwork from you.

The second half applies only if you pay tax above the basic rate, and you claim it, not the charity. Your basic rate band is extended by the grossed-up donation, so income that would have been taxed at 40% is taxed at 20% instead. On a £1,000 donation grossed up to £1,250, that is worth £250. An additional rate donor gets 25 percentage points instead of 20.

What the gift aid calculator does with your income

Instead of applying a flat percentage, the tool works out your Income Tax twice: once as normal, and once with the bands extended by the grossed-up donation. The difference is your relief. That handles the cases a flat percentage gets wrong, such as a donation that crosses a band boundary or one that takes a donor back into the basic rate entirely.

It also models the personal allowance taper, which matters most for donors earning between £100,000 and £125,140.

The £100,000 sweet spot

Between £100,000 and £125,140 the personal allowance is withdrawn at £1 for every £2 of income, creating a marginal tax rate of 60%. The taper is based on adjusted net income, and Gift Aid donations reduce adjusted net income by their grossed-up amount.

The result is generous. Someone earning £110,000 who donates £8,000 grosses it up to £10,000, bringing adjusted net income down to £100,000 and restoring the whole personal allowance. Their tax bill falls by £4,000: £2,000 from the extended band and £2,000 from the restored allowance, an effective relief rate of 50%. The charity receives £10,000, and the gift costs the donor £4,000.

You have to have paid the tax

You must have paid at least as much Income Tax or Capital Gains Tax in the tax year as all the charities you gave to will reclaim on your donations. The reclaim is a refund of tax you paid.

If your donations gross up to more tax than you actually paid, HMRC can ask you for the shortfall. Pensioners with income within the personal allowance, people whose only income is from ISAs and anyone taking a year out of work are the usual cases. Council Tax, VAT and National Insurance do not count. If you are in doubt, do not tick the Gift Aid box; the charity keeps your donation either way.

Where the relief actually lands

The higher rate relief comes to you, not the charity. It reduces your own tax bill, and you decide what to do with the saving. Many donors treat it as a rebate; others pass it on, which is how a £750 net cost can become £1,250 for the charity in the first example.

If you want the charity to get the full value, gross up the gift yourself. Donating £1,250 instead of £1,000 costs a higher rate taxpayer £937.50 after relief and gives the charity £1,562.50. Adjusting the donation until the net cost matches what you meant to give increases the gift without costing you more.

Gifts of shares or land work differently. They fall outside Gift Aid but get full Income Tax relief on the market value and are exempt from Capital Gains Tax, which can beat a cash gift for a donor holding assets that have risen in value.

Claiming the higher rate part

If you file a Self Assessment return, enter your total Gift Aid donations in the charitable giving section and the relief is included in the calculation. If you do not, ask HMRC to adjust your tax code, or claim in writing after the tax year ends.

Keep a record of what you gave and to whom. Payroll giving donations are already relieved at source and should not be entered again, and gifts to overseas charities qualify only if HMRC recognises the charity. You can also carry a donation back to the previous tax year on your return, which lets you claim relief at a higher rate if your income has since fallen.

Regular donors often forget the higher rate claim because the direct debit runs on its own. Add up a year of monthly gifts and enter the total here to see how much is unclaimed.

These figures are an estimate based on the 2026/27 Income Tax bands, personal allowance and taper thresholds, and assume all the income entered is taxable earnings. Dividends, savings interest and capital gains are taxed under their own rules and can change the result, so treat this as a guide rather than tax advice and check with HMRC or an adviser before filing.

About This Gift Aid Calculator

Use this gift Aid calculator to get an instant, accurate estimate. The figures follow official GOV.UK guidance and every rate and threshold is kept up to date for 2026. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.