In the UK, money you earn is taxed before you keep it. So when a taxpayer gives money to a charity, tax has already been taken out of that money once. Gift Aid lets the charity go to the government and claim that tax as well. The giver hands over the same amount as before; the charity ends up with more. To make it work, the giver has to say that they pay UK tax, usually by ticking a box or signing a short declaration. You will meet the words on donation forms, on charity shop receipts and on collection websites. It is a British system, so it only applies to people who pay tax in the UK.

Here the name of the scheme is used as a verb: you gift aid a donation. What you actually do is small — you say you pay UK tax and tick or sign something — and the scheme does the rest. It turns up most often as a question to a giver, would you like to gift aid your donation, and in the passive, your donation has been gift aided. The object is the money or the gift, not the charity: you gift aid a donation, not the shelter. Both the capitals and the spacing move around in real use, so you will see Gift Aid, gift aid and gift-aid all doing the same job.