Donors must pay UK tax in the year(s) they make donation(s) to your charity.
Gift Aid declarations
The conventional way to establish this is to obtain a declaration from the donor, stating they are a UK taxpayer and have paid enough tax to cover not only the donation(s) they've made to you, but all his or her donations.
Wordings differ slightly depending on whether the declaration is to cover a single donation or multiple donations over time and should indicate what is being Gift-Aided: whether it is a single gift or multiple gifts over several years. If the latter, it should indicate whether qualifying gifts in the past are to be included.
HMRC updated declaration wordings in October 2015. Declarations should also now state that the donor understands that he/she is responsible for repaying any tax if the amount they've paid does not cover what has been reclaimed.
Model declarations appear on HMRC's website. Bear in mind these are models and can be adapted as necessary. They need significant adaptation for use on envelopes. Our sister company, Envelope Systems, has extensive experience of designing and producing Gift Aid envelopes, what works and what to avoid. If you need assistance, the can be contacted on 01767 681717 or at enquiries@envelopesystems.co.uk.