diff --git a/services/identity/src/constants.rs b/services/identity/src/constants.rs
--- a/services/identity/src/constants.rs
+++ b/services/identity/src/constants.rs
@@ -91,6 +91,7 @@
   "usernameLower";
 pub const RESERVED_USERNAMES_TABLE_USERNAME_LOWER_INDEX: &str =
   "usernameLower-index";
+pub const RESERVED_USERNAMES_TABLE_USER_ID_INDEX: &str = "userID-index";
 
 // Users table social proof attribute
 pub const SOCIAL_PROOF_MESSAGE_ATTRIBUTE: &str = "siweMessage";
diff --git a/services/terraform/modules/shared/dynamodb.tf b/services/terraform/modules/shared/dynamodb.tf
--- a/services/terraform/modules/shared/dynamodb.tf
+++ b/services/terraform/modules/shared/dynamodb.tf
@@ -287,12 +287,23 @@
     type = "S"
   }
 
+  attribute {
+    name = "userID"
+    type = "S"
+  }
+
   global_secondary_index {
     name               = "usernameLower-index"
     hash_key           = "usernameLower"
     projection_type    = "INCLUDE"
     non_key_attributes = ["userID"]
   }
+
+  global_secondary_index {
+    name            = "userID-index"
+    hash_key        = "userID"
+    projection_type = "KEYS_ONLY"
+  }
 }
 
 resource "aws_dynamodb_table" "identity-one-time-keys" {