The charity predicts that the move will secure it an extra £1m annually within the next five years.
When people donate items to one of the charity's shops, they will be asked to fill in a Gift Aid form containing a tracking number. An automated system will prompt staff to write to the donor when the item is sold, detailing the amount raised and requesting permission to Gift Aid it.
Donor ID cards will allow supporters to donate more items using the same tracking number.
Alan Hodges, director of retail at Sue Ryder Care, said: "This could revolutionise the way charity shops operate."
A spokeswoman from the Association of Charity Shops said: "This could open the floodgates. Charities would be failing by not maximising their donations."