diff --git a/src/main/resources/interface-specification.yml b/src/main/resources/interface-specification.yml
index 7d202ab..d5e2848 100644
--- a/src/main/resources/interface-specification.yml
+++ b/src/main/resources/interface-specification.yml
@@ -824,8 +824,11 @@ components:
         id:
           type: string
           format: uuid
+        externalId:
+          $ref: '#/components/schemas/ExternalId'  
       required:
-        - id    
+        - id
+        - externalId
     Tenant:
       description: Tenant model
       type: object
diff --git a/src/main/scala/it/pagopa/interop/tenantprocess/api/impl/TenantApiServiceImpl.scala b/src/main/scala/it/pagopa/interop/tenantprocess/api/impl/TenantApiServiceImpl.scala
index 3be7dc5..1500558 100644
--- a/src/main/scala/it/pagopa/interop/tenantprocess/api/impl/TenantApiServiceImpl.scala
+++ b/src/main/scala/it/pagopa/interop/tenantprocess/api/impl/TenantApiServiceImpl.scala
@@ -238,7 +238,7 @@ final case class TenantApiServiceImpl(
       tenantKind     <- getTenantKindLoadingCertifiedAttributes(tenant.attributes, tenant.externalId)
       _              <- updateSelfcareId(tenant, tenantKind)
       _              <- tenantManagementService.addTenantMail(tenant.id, seed.digitalAddress.toDependency)
-    } yield TenantUUID(tenant.id)
+    } yield TenantUUID(tenant.id, tenant.externalId.toApi)
 
     onComplete(result) {
       selfcareUpsertTenantResponse[TenantUUID](operationLabel)(selfcareUpsertTenant200)