diff --git a/fast/stages/01-resman/billing.tf b/fast/stages/01-resman/billing.tf
index 3e2020e7..f69b9ad9 100644
--- a/fast/stages/01-resman/billing.tf
+++ b/fast/stages/01-resman/billing.tf
@@ -41,7 +41,8 @@ module "billing-organization-ext" {
   count           = local.billing_org_ext ? 1 : 0
   organization_id = "organizations/${var.billing_account.organization_id}"
   iam_additive = {
-    "roles/billing.user" = local.billing_ext_users
+    "roles/billing.user"         = local.billing_ext_users
+    "roles/billing.costsManager" = local.billing_ext_users
   }
 }
 
@@ -55,3 +56,12 @@ resource "google_billing_account_iam_member" "billing_ext_admin" {
   role               = "roles/billing.user"
   member             = each.key
 }
+
+resource "google_billing_account_iam_member" "billing_ext_costsmanager" {
+  for_each = toset(
+    local.billing_ext ? local.billing_ext_users : []
+  )
+  billing_account_id = var.billing_account.id
+  role               = "roles/billing.costsManager"
+  member             = each.key
+}