diff --git a/environments/prod/variables.tf b/environments/prod/variables.tf
index 2ce8f34..06d5dfb 100644
--- a/environments/prod/variables.tf
+++ b/environments/prod/variables.tf
@@ -25,4 +25,5 @@ variable "cost_center" {
 variable "slack_webhook_url" {
   description = "Slack webhook URL for notifications"
   type        = string
+  default     = ""
 }
diff --git a/modules/billing_report/data.tf b/modules/billing_report/data.tf
index 66d073b..f9499ad 100644
--- a/modules/billing_report/data.tf
+++ b/modules/billing_report/data.tf
@@ -10,3 +10,9 @@ data "archive_file" "lambda_zip" {
   source_file = "${path.module}/lambda_function.py"
   output_path = "${path.module}/lambda_function.zip"
 }
+
+# Retrieve the existing SSM parameter value
+data "aws_ssm_parameter" "existing_slack_webhook_url" {
+  name            = "/billing_report/slack_webhook_url"
+  with_decryption = true # Ensure we get the decrypted value
+}
\ No newline at end of file
diff --git a/modules/billing_report/main.tf b/modules/billing_report/main.tf
index b030921..a0fca67 100644
--- a/modules/billing_report/main.tf
+++ b/modules/billing_report/main.tf
@@ -263,9 +263,10 @@ resource "aws_sns_topic_subscription" "billing_report_email" {
   endpoint  = var.recipient_emails[count.index]
 }
 
-# Store Slack webhook URL securely in SSM Parameter Store
+# Create or update the SSM parameter
 resource "aws_ssm_parameter" "slack_webhook_url" {
   name  = "/billing_report/slack_webhook_url"
-  type  = "SecureString"
-  value = var.slack_webhook_url
-}
+  type  = "SecureString" # Store the value as an encrypted string
+  value = var.slack_webhook_url != "" ? var.slack_webhook_url : data.aws_ssm_parameter.existing_slack_webhook_url.value
+  # Use the new value if provided, otherwise keep the existing value
+}
\ No newline at end of file