diff --git a/core/lib/Thelia/Controller/Admin/CouponController.php b/core/lib/Thelia/Controller/Admin/CouponController.php
index db199c23a..94c84775c 100644
--- a/core/lib/Thelia/Controller/Admin/CouponController.php
+++ b/core/lib/Thelia/Controller/Admin/CouponController.php
@@ -633,8 +633,9 @@ class CouponController extends BaseAdminController
             }
 
             $response = new ResponseRest($couponManager->drawBackOfficeInputs());
-        }
-        else {
+        } else {
+            // Return an empty response if the service ID is not defined
+            // Typically, when the user chooses "Please select a coupon type"
             $response = new ResponseRest('');
         }
 
diff --git a/core/lib/Thelia/Coupon/Type/CouponAbstract.php b/core/lib/Thelia/Coupon/Type/CouponAbstract.php
index d04c29b89..02336cc2e 100644
--- a/core/lib/Thelia/Coupon/Type/CouponAbstract.php
+++ b/core/lib/Thelia/Coupon/Type/CouponAbstract.php
@@ -402,7 +402,8 @@ abstract class CouponAbstract implements CouponInterface
      *
      * @return string
      */
-    public function getInputName() {
+    public function getInputName()
+    {
         return "Please override getInputName() method";
     }
 
@@ -434,33 +435,32 @@ abstract class CouponAbstract implements CouponInterface
      * @return mixed
      * @throws \InvalidArgumentException if the field valiue is not valid.
      */
-    protected function checkCouponFieldValue($fieldName, $fieldValue) {
+    protected function checkCouponFieldValue($fieldName, $fieldValue)
+    {
         return $fieldValue;
     }
 
     /**
      * A helper to get the value of a standard field name
      *
-     * @param string $fieldName the field name
-     * @param array $data the input form data (e.g. $form->getData())
-     * @param mixed $defaultValue the default value if the field is not found.
+     * @param string $fieldName    the field name
+     * @param array  $data         the input form data (e.g. $form->getData())
+     * @param mixed  $defaultValue the default value if the field is not found.
      *
      * @return mixed the input value, or the default one
      *
      * @throws \InvalidArgumentException if the field is not found, and no default value has been defined.
      */
-    protected function getCouponFieldValue($fieldName, $data, $defaultValue = null) {
+    protected function getCouponFieldValue($fieldName, $data, $defaultValue = null)
+    {
         if (isset($data[self::COUPON_DATASET_NAME][$fieldName])) {
-
             return $this->checkCouponFieldValue(
                 $fieldName,
                 $data[self::COUPON_DATASET_NAME][$fieldName]
             );
-        }
-        else if (null !== $defaultValue) {
+        } elseif (null !== $defaultValue) {
             return $defaultValue;
-        }
-        else {
+        } else {
             throw new \InvalidArgumentException(sprintf("The coupon field name %s was not found in the coupon form", $fieldName));
         }
     }
@@ -468,10 +468,11 @@ abstract class CouponAbstract implements CouponInterface
     /**
      * A helper to create an standard field name that will be used in the coupon form
      *
-     * @param string $fieldName the field name
+     * @param  string $fieldName the field name
      * @return string the complete name, ready to be used in a form.
      */
-    protected function makeCouponFieldName($fieldName) {
+    protected function makeCouponFieldName($fieldName)
+    {
         return sprintf("%s[%s][%s]", CouponCreationForm::COUPON_CREATION_FORM_NAME, self::COUPON_DATASET_NAME, $fieldName);
     }
 
@@ -480,20 +481,22 @@ abstract class CouponAbstract implements CouponInterface
      *
      * @return array
      */
-    protected function getFieldList() {
+    protected function getFieldList()
+    {
         return [self::AMOUNT_FIELD_NAME];
     }
 
     /**
      * Create the effect array from the list of fields
      *
-     * @param array $data the input form data (e.g. $form->getData())
+     * @param  array $data the input form data (e.g. $form->getData())
      * @return array a filedName => fieldValue array
      */
-    public function getEffects($data) {
+    public function getEffects($data)
+    {
         $effects = [];
 
-        foreach($this->getFieldList() as $fieldName) {
+        foreach ($this->getFieldList() as $fieldName) {
             $effects[$fieldName] = $this->getCouponFieldValue($fieldName, $data);
         }
 
diff --git a/core/lib/Thelia/Coupon/Type/CouponInterface.php b/core/lib/Thelia/Coupon/Type/CouponInterface.php
index f9acc973d..a9382749f 100644
--- a/core/lib/Thelia/Coupon/Type/CouponInterface.php
+++ b/core/lib/Thelia/Coupon/Type/CouponInterface.php
@@ -15,7 +15,6 @@ namespace Thelia\Coupon\Type;
 use Propel\Runtime\Collection\ObjectCollection;
 use Thelia\Condition\ConditionCollection;
 use Thelia\Coupon\FacadeInterface;
-use Thelia\Form\CouponCreationForm;
 
 /**
  * Represents a Coupon ready to be processed in a Checkout process
diff --git a/core/lib/Thelia/Coupon/Type/RemoveAmountOnCategories.php b/core/lib/Thelia/Coupon/Type/RemoveAmountOnCategories.php
index 9994219e2..665a02bff 100644
--- a/core/lib/Thelia/Coupon/Type/RemoveAmountOnCategories.php
+++ b/core/lib/Thelia/Coupon/Type/RemoveAmountOnCategories.php
@@ -14,6 +14,8 @@ namespace Thelia\Coupon\Type;
 
 use Thelia\Core\Translation\Translator;
 use Thelia\Coupon\FacadeInterface;
+use Thelia\Model\CartItem;
+use Thelia\Model\Category;
 
 /**
  * Allow to remove an amount from the checkout total
@@ -29,7 +31,7 @@ class RemoveAmountOnCategories extends CouponAbstract
     /** @var string Service Id  */
     protected $serviceId = 'thelia.coupon.type.remove_amount_on_categories';
 
-    var $category_list = array();
+    public $category_list = array();
 
     /**
      * @inheritdoc
@@ -105,8 +107,29 @@ class RemoveAmountOnCategories extends CouponAbstract
      */
     public function exec()
     {
-        // TODO !!!
-        return $this->amount;
+        // This coupon subtracts the specified amount from the order total
+        // for each product of the selected categories.
+        $discount = 0;
+
+        $cartItems = $this->facade->getCart()->getCartItems();
+
+        /** @var CartItem $cartItem */
+        foreach ($cartItems as $cartItem) {
+
+            $categories = $cartItem->getProduct()->getCategories();
+
+            /** @var Category $category */
+            foreach ($categories as $category) {
+
+                if (in_array($category->getId(), $this->category_list)) {
+                    $discount += $cartItem->getQuantity() * $this->amount;
+
+                    break;
+                }
+            }
+        }
+
+        return $discount;
     }
 
     public function drawBackOfficeInputs()
@@ -131,11 +154,11 @@ class RemoveAmountOnCategories extends CouponAbstract
      *
      * @return array
      */
-    protected function getFieldList() {
+    protected function getFieldList()
+    {
         return [self::AMOUNT_FIELD_NAME, self::CATEGORIES_LIST];
     }
 
-
     /**
      * @inheritdoc
      */
@@ -151,8 +174,7 @@ class RemoveAmountOnCategories extends CouponAbstract
                     )
                 );
             }
-        }
-        else if ($fieldName === self::CATEGORIES_LIST) {
+        } elseif ($fieldName === self::CATEGORIES_LIST) {
             if (empty($fieldValue)) {
                 throw new \InvalidArgumentException(
                     Translator::getInstance()->trans(
diff --git a/core/lib/Thelia/Coupon/Type/RemoveXAmount.php b/core/lib/Thelia/Coupon/Type/RemoveXAmount.php
index fe5322e22..1f83c6eec 100644
--- a/core/lib/Thelia/Coupon/Type/RemoveXAmount.php
+++ b/core/lib/Thelia/Coupon/Type/RemoveXAmount.php
@@ -69,7 +69,8 @@ class RemoveXAmount extends CouponAbstract
      *
      * @return array
      */
-    protected function getFieldList() {
+    protected function getFieldList()
+    {
         return [self::AMOUNT_FIELD_NAME];
     }
 
@@ -93,4 +94,4 @@ class RemoveXAmount extends CouponAbstract
         return $fieldValue;
     }
 
-}
\ No newline at end of file
+}
diff --git a/core/lib/Thelia/Coupon/Type/RemoveXPercent.php b/core/lib/Thelia/Coupon/Type/RemoveXPercent.php
index 06c73981a..e1cc20252 100644
--- a/core/lib/Thelia/Coupon/Type/RemoveXPercent.php
+++ b/core/lib/Thelia/Coupon/Type/RemoveXPercent.php
@@ -152,7 +152,8 @@ class RemoveXPercent extends CouponAbstract
      *
      * @return array
      */
-    protected function getFieldList() {
+    protected function getFieldList()
+    {
         return [self::INPUT_PERCENTAGE_NAME];
     }
 }