diff --git a/docs/resources/resourcemanager_project.md b/docs/resources/resourcemanager_project.md
index 382cc2f78..4acebbbb2 100644
--- a/docs/resources/resourcemanager_project.md
+++ b/docs/resources/resourcemanager_project.md
@@ -21,7 +21,10 @@ resource "stackit_resourcemanager_project" "example" {
   name                = "example-container"
   labels = {
     "Label 1" = "foo"
-    // "networkArea" = stackit_network_area.foo.network_area_id
+    # "networkArea" = stackit_network_area.foo.network_area_id
+
+    # optional - you can set a billing reference by adding a label with the 'billingReference' key
+    "billingReference" = "fooref"
   }
   owner_email = "john.doe@stackit.cloud"
 }
diff --git a/examples/resources/stackit_resourcemanager_project/resource.tf b/examples/resources/stackit_resourcemanager_project/resource.tf
index 37bcc4c05..17a3ecab8 100644
--- a/examples/resources/stackit_resourcemanager_project/resource.tf
+++ b/examples/resources/stackit_resourcemanager_project/resource.tf
@@ -3,7 +3,10 @@ resource "stackit_resourcemanager_project" "example" {
   name                = "example-container"
   labels = {
     "Label 1" = "foo"
-    // "networkArea" = stackit_network_area.foo.network_area_id
+    # "networkArea" = stackit_network_area.foo.network_area_id
+
+    # optional - you can set a billing reference by adding a label with the 'billingReference' key
+    "billingReference" = "fooref"
   }
   owner_email = "john.doe@stackit.cloud"
 }