diff --git a/buds/07.md b/buds/07.md
index 516c093..8b5dde3 100644
--- a/buds/07.md
+++ b/buds/07.md
@@ -85,6 +85,10 @@ Example for Lightning:
 X-Lightning: "966fcb8f153339372f9a187f725384ff4ceae0047c25b9ce607488d7c7e93bba"
 ```
 
+**Special Note on HEAD Requests**
+
+The HEAD endpoints are only used to retrieve blob or server information. They MUST NOT be retried with payment proof. Instead, clients should complete the payment and proceed with the `PUT` or `GET` request.
+
 ### Recurring Payments
 
 Servers MAY accept recurring payments for blob storage using the following Nostr event types:
@@ -99,7 +103,7 @@ The event MUST include a custom `x` tag containing the hash of the blob being pa
 
 ### Error handling
 
-If the client fails to provide the payment proof (expired invoice, invalid token, etc.) the server MUST respond with **402 Payment Required** status code and include the relevant `X-{payment_method}` header(s) with updated payment details.
+If the client fails to provide the payment proof (expired invoice, invalid token, etc.) the server MUST respond with **400 Bad request** status code and include a `X-Reason` header with a human-readable message. The client SHOULD inform the user about the error and provide a way to retry the request.
 
 ### Extending with Future Payment Methods