Gift Aid is only for donations by the donor. It cannot be claimed on other people's donations - for example, if someone collects money from several people, each person would have to make a Gift Aid declaration for their portion. It also cannot be claimed for money where the donor received something in return, e.g. purchasing goods from a charity store, or buying a ticket in a charity raffle, as these are not strictly donations. In the case of donated goods, Gift Aid can still be claimed via the donor of the goods, not the purchaser.