diff --git a/src/main/java/de/financer/ResponseReason.java b/src/main/java/de/financer/ResponseReason.java
index 88532a1..01a1025 100644
--- a/src/main/java/de/financer/ResponseReason.java
+++ b/src/main/java/de/financer/ResponseReason.java
@@ -29,7 +29,8 @@ public enum ResponseReason {
     MISSING_TRANSACTION_ID(HttpStatus.INTERNAL_SERVER_ERROR),
     INVALID_TRANSACTION_ID(HttpStatus.INTERNAL_SERVER_ERROR),
     TRANSACTION_NOT_FOUND(HttpStatus.INTERNAL_SERVER_ERROR),
-    ACCOUNT_NOT_FOUND(HttpStatus.INTERNAL_SERVER_ERROR);
+    ACCOUNT_NOT_FOUND(HttpStatus.INTERNAL_SERVER_ERROR),
+    DUPLICATE_ACCOUNT_KEY(HttpStatus.INTERNAL_SERVER_ERROR);
 
     private HttpStatus httpStatus;
 
diff --git a/src/main/resources/i18n/message.properties b/src/main/resources/i18n/message.properties
index b39ad02..791ee78 100644
--- a/src/main/resources/i18n/message.properties
+++ b/src/main/resources/i18n/message.properties
@@ -143,4 +143,5 @@ financer.error-message.RECURRING_TRANSACTION_NOT_FOUND=The recurring transaction
 financer.error-message.MISSING_TRANSACTION_ID=No transaction entered!
 financer.error-message.INVALID_TRANSACTION_ID=The transaction is not valid!
 financer.error-message.TRANSACTION_NOT_FOUND=The transaction could not be found!
-financer.error-message.ACCOUNT_NOT_FOUND=The account could not be found!
\ No newline at end of file
+financer.error-message.ACCOUNT_NOT_FOUND=The account could not be found!
+financer.error-message.DUPLICATE_ACCOUNT_KEY=An account with the  given key already exists!
\ No newline at end of file