diff --git a/README.md b/README.md
index 0d5c713..1fc0a07 100644
--- a/README.md
+++ b/README.md
@@ -212,4 +212,4 @@ resource "aws_rds_cluster_parameter_group" "aurora_cluster_postgres96_parameter_
 | cluster_endpoint | The 'writer' endpoint for the cluster |
 | reader_endpoint | A read-only endpoint for the Aurora cluster, automatically load-balanced across replicas |
 | cluster_arn | ARN of the cluster, useful when defining centralised backup script |
-
+| cluster_id | ID of the cluster, useful to any resources requiring cluster's ID, e.g. rds_cluster_role_association |
diff --git a/outputs.tf b/outputs.tf
index d5a7a94..ac89aa7 100644
--- a/outputs.tf
+++ b/outputs.tf
@@ -16,4 +16,9 @@ output "reader_endpoint" {
 // Cluster ARN - can use when defining centralised backup
 output "cluster_arn" {
   value = "${aws_rds_cluster.default.arn}"
+}
+
+// Cluster ID - useful to any resources requiring cluster's ID, e.g. rds_cluster_role_association
+output "cluster_id" {
+  value = "${aws_rds_cluster.default.id}"
 }
\ No newline at end of file