ACM doesn't provide managed renewal for imported certificates, expired certificates, or private certificates that AWS Private Certificate Authority issues with the IssueCertificate API call. ACM does provide managed renewal for private certificates that AWS Private CA issues from the ACM console.
Action required by domain owner
ACM certificates are valid for 13 months (395 days). ACM uses the domain's WHOIS mailbox addresses and up to five common administrator addresses to send renewal notices 45 days before expiration. To renew the certificate, you must use the link that's in the email notification. After all listed domains are validated, ACM issues a renewed certificate with the same ARN.