Gift Aid is a program of HM Revenue & Customs (HMRC) that enables not-for-profit organisations to claim back the basic rate tax paid by donors. In effect, electing to donate with a Gift Aid declaration increases your gift to the organisation at no additional cost to you.
Note: The Gift Aid declaration is governed by a 4-year rule that limits tax claims for donations to within four years of the end of the financial period in which the donations are received. This means that donations made outside of that period are not included in the Gift Aid claim.
Gift Aid is for monetary donations by individuals who pay UK tax. Charities in the UK, EU, Norway, and Iceland can be eligible for Gift Aid. Charities take the donation (on which the donor has already paid tax), and reclaim the basic rate tax on its gross equivalent (the amount before basic rate tax was deducted).
Visit GOV.UK for the official information about Gift Aid. To learn more about how Gift Aid donations are calculated, visit one of the many gift-aid calculators online.