Only citizens over 16 who have received one or both doses of their covid vaccination in NI can apply for a certificate. The NI COVID certificate is valid for six months from the date of application. Digital certificates will automatically renew a week before they are due to expire. Paper certificates will be posted out a week before they are due to expire. There is a process under development to allow parents to apply on behalf of their children which will be available on the 27th January.