Let’s Encrypt to Reduce Certificate Validity from 90 Days to 45 Days Let’s Encrypt has officially announced plans to reduce the maximum validity period of its SSL/TLS certificates from 90 days to 45 days. The transition, which will be completed by 2028, aligns with broader industry shifts mandated by the CA/Browser Forum Baseline Requirements. This move is designed to enhance internet security by limiting the window of compromise for stolen credentials and improving the efficiency of certificate revocation technologies.