diff --git a/15-draft.json b/15-draft.json
index dfca634..18581f8 100644
--- a/15-draft.json
+++ b/15-draft.json
@@ -1449,6 +1449,7 @@
             "type": "string",
             "enum": [
               "yearly",
+              "quarterly",
               "monthly",
               "weekly",
               "daily",
diff --git a/CHANGELOG.md b/CHANGELOG.md
index da47f54..db76468 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -36,6 +36,10 @@ Root level:
 
 - [changed] Clarify that `lastchange` unit is in seconds ([#98])
 
+`membership_plans`:
+
+- [added] The `quarterly` enum value was added to `billing_interval`
+
 ## v14
 
 Root level: