If HMRC recognises you as a charity or CASC, you may enable Gift Aid for online donations via GivenGain. Log in to your charity account on GivenGain under "Settings > Account" and tick the "Enable Gift Aid support for GBP donations" option. This provides donors with the option to include Gift Aid as part of their donations.
All Gift Aid donation declarations and schedules are available in your GivenGain charity account, under Reports > Gift Aid. To claim Gift Aid, export this information and submit it to HMRC online at https://www.gov.uk/claim-gift-aid-online. You should receive payment within 5 weeks.
Visit the HMRC website to find out more about claiming Gift Aid as a charity.