diff --git a/changelog.d/17515.doc b/changelog.d/17515.doc
new file mode 100644
index 0000000000..c2dbe24e9d
--- /dev/null
+++ b/changelog.d/17515.doc
@@ -0,0 +1,3 @@
+Clarify default behaviour of the
+[`auto_accept_invites.worker_to_run_on`](https://element-hq.github.io/synapse/develop/usage/configuration/config_documentation.html#auto-accept-invites)
+option.
\ No newline at end of file
diff --git a/docs/usage/configuration/config_documentation.md b/docs/usage/configuration/config_documentation.md
index 40f64be856..567bbf88d2 100644
--- a/docs/usage/configuration/config_documentation.md
+++ b/docs/usage/configuration/config_documentation.md
@@ -4685,7 +4685,9 @@ This setting has the following sub-options:
 * `only_for_direct_messages`: Whether invites should be automatically accepted for all room types, or only
    for direct messages. Defaults to false.
 * `only_from_local_users`: Whether to only automatically accept invites from users on this homeserver. Defaults to false.
-* `worker_to_run_on`: Which worker to run this module on. This must match the "worker_name".
+* `worker_to_run_on`: Which worker to run this module on. This must match 
+  the "worker_name". If not set or `null`, invites will be accepted on the
+  main process.
 
 NOTE: Care should be taken not to enable this setting if the `synapse_auto_accept_invite` module is enabled and installed.
 The two modules will compete to perform the same task and may result in undesired behaviour. For example, multiple join