diff --git a/src/Controller/TransactionCreationsController.php b/src/Controller/TransactionCreationsController.php
index 951ac14af..5e29a7997 100644
--- a/src/Controller/TransactionCreationsController.php
+++ b/src/Controller/TransactionCreationsController.php
@@ -483,6 +483,9 @@ class TransactionCreationsController extends AppController
             if($amount > 10000000) {
                 return $this->returnJson(['state' => 'error', 'msg' => 'amount is to big']);
             }
+            if($amount <= 0) {
+                return $this->returnJson(['state' => 'error', 'msg' => 'amount must be > 0']);
+            }
             if(!isset($jsonData['target_date'])) {
                 return $this->returnJson(['state' => 'parameter missing', 'msg' => 'target_date not found']);
             }
diff --git a/src/Controller/TransactionSendCoinsController.php b/src/Controller/TransactionSendCoinsController.php
index a6fab144c..e99dd4f13 100644
--- a/src/Controller/TransactionSendCoinsController.php
+++ b/src/Controller/TransactionSendCoinsController.php
@@ -313,6 +313,9 @@ class TransactionSendCoinsController extends AppController
             if(!isset($jsonData['amount']) || !isset($jsonData['email'])) {
                 return $this->returnJson(['state' => 'parameter missing', 'msg' => 'amount and/or email not set']);
             }
+            if($jsonData['amount'] < 0) {
+                return $this->returnJson(['state' => 'error', 'msg' => 'amout must be > 0']);
+            }
             
             if(!isset($user['balance']) || $jsonData['amount'] > $user['balance']) {
               return $this->returnJson(['state' => 'error', 'msg' => 'not enough GDD']);
diff --git a/src/Model/Transactions/TransactionCreation.php b/src/Model/Transactions/TransactionCreation.php
index 2bd326ea7..e9feed4e9 100644
--- a/src/Model/Transactions/TransactionCreation.php
+++ b/src/Model/Transactions/TransactionCreation.php
@@ -189,6 +189,12 @@ class TransactionCreation extends TransactionBase {
           return false;
         }
      } else {*/
+       if($newSum2 <= 0) {
+           $this->addError(
+                'TransactionCreation::validate',
+                'Creation less than 0 GDD per Month for '. $receiverEmail .' in target_date not allowed'   
+           );
+       }
        if($newSum2 > 10000000) {
          $this->addError(
                  'TransactionCreation::validate',
diff --git a/src/Model/Transactions/TransactionTransfer.php b/src/Model/Transactions/TransactionTransfer.php
index 8ad726d53..d22dbadef 100644
--- a/src/Model/Transactions/TransactionTransfer.php
+++ b/src/Model/Transactions/TransactionTransfer.php
@@ -154,6 +154,10 @@ class TransactionTransfer extends TransactionBase {
         $this->addError($functionName, 'sender amount doesn\'t match receiver amount');
         return false;
       }
+      if($senderSum < 0) {
+          $this->addError($functionName, 'negative amount not supported');
+          return false;
+      }
       //die("\n");
       return true;
     }