diff --git a/S3-Bucket-Quota.md b/S3-Bucket-Quota.md
index b887fe8..a5d1107 100644
--- a/S3-Bucket-Quota.md
+++ b/S3-Bucket-Quota.md
@@ -61,6 +61,8 @@ Note: Internally this readOnly flag is saved into filer configuration for `locat
 }
 ```
 
+Over-quota writes (`PutObject`, `UploadPart`, `CopyObject`, `UploadPartCopy`) fail with `403 AccessDenied`, not `500`. Do not retry — the request cannot succeed until usage drops back under quota or the quota is raised.
+
 # Schedule Quota Enforcement
 
 `s3.bucket.quota.enforce -apply` should be run regularly. You can add it to the `master.toml` file, or add it to some shell scripts. The frequency depends on how much you trust your users. :)