What happens when my certificate expires?
If you allow a certificate to expire, the certificate becomes invalid, and you will no longer be able to run secure transactions on your website. The Certification Authority (CA) will prompt you to renew your SSL certificate prior to the expiration date.
NOTE: A certificate can only be renewed up to 120 days prior to and 30 days following the expiration date. You can apply the renewal credit 60 days before expiration or 30 days after expiration.
What is a Premium Extended Validation (EV) SSL certificate?
What is domain control validation?
What If I notice a problem with an SSL certificate?
What is a Wildcard SSL certificate?
Information About Requiring the SHA-2 Hash Function
How does ICANN's New gTLD Program affect my SSL certificate?