diff --git a/moto/organizations/models.py b/moto/organizations/models.py
index <HASH>..<HASH> 100644
--- a/moto/organizations/models.py
+++ b/moto/organizations/models.py
@@ -157,6 +157,11 @@ class OrganizationsBackend(BaseBackend):
         return self.org.describe()
 
     def describe_organization(self):
+        if not self.org:
+            raise RESTError(
+                'AWSOrganizationsNotInUseException',
+                "Your account is not a member of an organization."
+            )
         return self.org.describe()
 
     def list_roots(self):
organizations support: add exception handling for describe_organizations