diff --git a/.changelog/6747.txt b/.changelog/6747.txt
new file mode 100644
index 0000000000..4e232df080
--- /dev/null
+++ b/.changelog/6747.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+appengine: Fixed permadiff on serviceaccount for 'google_app_engine_flexible_app_version'
+```
diff --git a/google/resource_app_engine_flexible_app_version.go b/google/resource_app_engine_flexible_app_version.go
index 0df504e426..939118b15d 100644
--- a/google/resource_app_engine_flexible_app_version.go
+++ b/google/resource_app_engine_flexible_app_version.go
@@ -803,6 +803,7 @@ Substitute '<language>' with 'python', 'java', 'php', 'ruby', 'go' or 'nodejs'.`
 			},
 			"service_account": {
 				Type:     schema.TypeString,
+				Computed: true,
 				Optional: true,
 				Description: `The identity that the deployed version will run as. Admin API will use the App Engine Appspot service account as
 default if this field is neither provided in app.yaml file nor through CLI flag.`,