Apple Developer News posted a notice on October 1, 2026, about the upcoming expiration of the original Developer ID Certification Authority (Sub-CA). Certificates issued by that authority stop working on February 1, 2027.
Apple tells developers to check whether they are affected by looking in Certificates, Identifiers & Profiles for certificates expiring on or before February 1, 2027. The replacement comes from the current authority, Developer ID Certification Authority (G2), which Apple says is valid until 2031. Certificates issued from it expire annually and must be renewed each year. When prompted for a Developer ID Certificate Intermediary, developers should pick G2 Sub-CA, because another choice may issue a certificate that also expires in 2027. Developers on Xcode 11.4 or earlier should update first.
What breaks depends on what is distributed. Starting February 1, 2027, installer packages (.pkg) signed with an affected certificate will no longer install, so Apple says to re-sign all packages with the new certificate before then. Mac software that was already signed and notarized with a secure timestamp keeps working, and no action is needed for it. Future updates should be signed with the new certificate and include a secure timestamp for notarization.
This brief reports Apple's notice only. It covers developers who distribute macOS software outside the Mac App Store and does not change anything for people who only install apps.