Let’s Encrypt is introducing significant changes to its certificates. The certificate authority is taking steps towards shorter certificate lifespans, new root certificates, and the end of TLS client authentication. The changes are in line with new CA/Browser Forum requirements.
Let’s Encrypt is generating two new Root Certification Authorities (CAs) and six new Intermediate CAs, collectively referred to as the Generation Y hierarchy. These are cross-signed from the existing Generation X roots X1 and X2. As a result, they will continue to work in places where the current roots are trusted.
Most users will receive certificates from the ‘classic’ profile by default, unless they consciously choose a different profile. This profile will switch to the Generation Y hierarchy on May 13, 2026. These new intermediates no longer contain the Extended Key Usage for TLS Client Authentication due to upcoming root program requirements. These are requirements set by browser vendors and operating system builders such as Google, Microsoft, Apple, and Mozilla. CAs must comply with these requirements, which are becoming increasingly stringent. In this case, the issuance of TLS certificates will be server-only, meaning that client-based provision of certificates will no longer be permitted.
Previous plans implemented
Let’s Encrypt previously announced that it would discontinue TLS Client Authentication from February 2026. This will happen simultaneously with the switch to Generation Y. Users who encounter problems or need more time can use the tlsclient profile until May 2026. This will continue to run on the Generation X roots.
Users who request certificates via the tlsserver or short-lived profiles will receive certificates from the Generation Y hierarchy starting this week. This switch also marks the opt-in availability of short-lived certificates at Let’s Encrypt. Support for IP addresses on certificates will also be added.
Broader support for shortening
The changes are in line with upcoming changes in the CA/Browser Forum Baseline Requirements. These require certificate authorities to shorten the validity period of certificates. Next year, early adopters and test users will be able to opt for 45-day certificates via the tlsserver profile.
In 2027, Let’s Encrypt will reduce the standard certificate lifetime to 64 days, followed by 45 days in 2028. In April, the broader CA/Browser Forum voted for a gradual reduction to 47 days in March 2029. Let’s Encrypt has opted for 45 days.
The reduction in certificate lifetimes is intended to improve security. More frequent validation reduces the risk of compromised certificates. It also compensates for weaknesses in revocation systems such as CRL and OCSP.
No action is required for most users, but Let’s Encrypt recommends reading the linked blog posts about the changes for more details.
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