diff --git a/BRANCHES.md b/BRANCHES.md
index a2ea074..0aaacb0 100644
--- a/BRANCHES.md
+++ b/BRANCHES.md
@@ -23,6 +23,11 @@
 compatibility on major version changes (e.g. from 3.x to 4.0). We also maintain
 ABI compatibility within LTS branches; see the next section for details.
 
+Every major version will become an LTS branch when the next major version is
+released. We may occasionally create LTS branches from other releases at our
+discretion.
+When a new LTS branch is created, it usually remains supported for three years.
+
 ## Backwards Compatibility for application code
 
 We maintain API compatibility in released versions of Mbed TLS. If you have