Hey,

There are usually two types of certificate

1- The certificate with no expiry like birth certificate, death, certificate, address certificate, etc.

2- The certificate with expiry date like income certificate, EWS reservation certificate, etc.

If your certificate falls in the second category you need to keep on updating it from time to time. It's not allowed to use the expired certificate. The admission authorities will have complete right to reject your certificate and that may also hamper your admission.

Hope that helps.

Thank you.