Gift aid is an income tax relief scheme, whereby tax paying individuals can offset charitable donations against their taxable income. The registered charities are able to reclaim tax on any donation they receive, both parties benefit from gift aid.
If you are a basic rate taxpayer and make a £30 cash donation the charity can reclaim a further £5 in tax thus bringing the total up to £35. Gift aid can also be applied to donated items, charities have the ability to reclaim tax on items they sell.
Please note that donors are required to make a declaration to say they are a UK taxpayer.