diff --git a/atst/domain/csp/cloud/azure_cloud_provider.py b/atst/domain/csp/cloud/azure_cloud_provider.py
index 5d6e91d8..5d9ca275 100644
--- a/atst/domain/csp/cloud/azure_cloud_provider.py
+++ b/atst/domain/csp/cloud/azure_cloud_provider.py
@@ -798,7 +798,7 @@ class AzureCloudProvider(CloudProviderInterface):
             graph_token, billing_admin_role_id, user_result.id
         )
 
-        return BillingOwnerCSPResult(id=user_result.id)
+        return BillingOwnerCSPResult(billing_owner_id=user_result.id)
 
     def _assign_billing_owner_role(self, graph_token, billing_admin_role_id, user_id):
         request_body = {
diff --git a/atst/domain/csp/cloud/mock_cloud_provider.py b/atst/domain/csp/cloud/mock_cloud_provider.py
index 7ec0636f..3454ec74 100644
--- a/atst/domain/csp/cloud/mock_cloud_provider.py
+++ b/atst/domain/csp/cloud/mock_cloud_provider.py
@@ -18,6 +18,8 @@ from .models import (
     ApplicationCSPResult,
     BillingInstructionCSPPayload,
     BillingInstructionCSPResult,
+    BillingOwnerCSPPayload,
+    BillingOwnerCSPResult,
     BillingProfileCreationCSPPayload,
     BillingProfileCreationCSPResult,
     BillingProfileTenantAccessCSPResult,
@@ -366,6 +368,13 @@ class MockCloudProvider(CloudProviderInterface):
 
         return PrincipalAdminRoleCSPResult(**dict(id="principal_assignment_id"))
 
+    def create_billing_owner(self, payload: BillingOwnerCSPPayload):
+        self._maybe_raise(self.NETWORK_FAILURE_PCT, self.NETWORK_EXCEPTION)
+        self._maybe_raise(self.SERVER_FAILURE_PCT, self.SERVER_EXCEPTION)
+        self._maybe_raise(self.UNAUTHORIZED_RATE, self.AUTHORIZATION_EXCEPTION)
+
+        return BillingOwnerCSPResult(billing_owner_id="foo")
+
     def create_or_update_user(self, auth_credentials, user_info, csp_role_id):
         self._authorize(auth_credentials)
 
diff --git a/atst/domain/csp/cloud/models.py b/atst/domain/csp/cloud/models.py
index b4920856..4656c432 100644
--- a/atst/domain/csp/cloud/models.py
+++ b/atst/domain/csp/cloud/models.py
@@ -580,4 +580,4 @@ class BillingOwnerCSPPayload(BaseCSPPayload, UserMixin):
 
 
 class BillingOwnerCSPResult(AliasModel):
-    id: str
+    billing_owner_id: str
diff --git a/atst/models/mixins/state_machines.py b/atst/models/mixins/state_machines.py
index a7edf268..8342853a 100644
--- a/atst/models/mixins/state_machines.py
+++ b/atst/models/mixins/state_machines.py
@@ -26,6 +26,7 @@ class AzureStages(Enum):
     PRINCIPAL_ADMIN_ROLE = "tenant principal admin"
     TENANT_ADMIN_OWNERSHIP = "tenant admin ownership"
     TENANT_PRINCIPAL_OWNERSHIP = "tenant principial ownership"
+    BILLING_OWNER = "billing owner"
 
 
 def _build_csp_states(csp_stages):
diff --git a/tests/domain/test_portfolio_state_machine.py b/tests/domain/test_portfolio_state_machine.py
index 2c27cfd8..5c7ca25c 100644
--- a/tests/domain/test_portfolio_state_machine.py
+++ b/tests/domain/test_portfolio_state_machine.py
@@ -113,6 +113,7 @@ def test_fsm_transition_start(mock_cloud_provider, portfolio: Portfolio):
         FSMStates.PRINCIPAL_ADMIN_ROLE_CREATED,
         FSMStates.TENANT_ADMIN_OWNERSHIP_CREATED,
         FSMStates.TENANT_PRINCIPAL_OWNERSHIP_CREATED,
+        FSMStates.BILLING_OWNER_CREATED,
     ]
 
     if portfolio.csp_data is not None: