Does the sack or leaflet say the collection is for a registered charity?
Firstly, look for a Charity Registration number. This is not the same as the Company Registration number. If you can’t find one or you are still not sure, call the Charity Commission on 0845 300 0218, and ask them to help you. Alternatively, visit the online Register of Charities to check that it is genuine. Many charities running shops collect house-to-house and their collection sacks will clearly state their charity registration number and many will also carry the Association’s Code of Charity Retailing logo.