diff --git a/core/lib/Thelia/Exception/TaxEngineException.php b/core/lib/Thelia/Exception/TaxEngineException.php
index 8ce8561ef..93f5b8237 100755
--- a/core/lib/Thelia/Exception/TaxEngineException.php
+++ b/core/lib/Thelia/Exception/TaxEngineException.php
@@ -30,9 +30,15 @@ class TaxEngineException extends \RuntimeException
     const BAD_RECORDED_TYPE = 101;
     const BAD_RECORDED_REQUIREMENTS = 102;
 
+    const TAX_TYPE_BAD_ABSTRACT_METHOD = 201;
+    const TAX_TYPE_REQUIREMENT_NOT_FOUND = 202;
+    const TAX_TYPE_BAD_REQUIREMENT_VALUE = 203;
+
     const UNDEFINED_PRODUCT = 501;
     const UNDEFINED_COUNTRY = 502;
     const UNDEFINED_TAX_RULES_COLLECTION = 503;
+    const UNDEFINED_REQUIREMENTS = 504;
+    const UNDEFINED_REQUIREMENT_VALUE = 505;
 
     const BAD_AMOUNT_FORMAT = 601;
 
diff --git a/core/lib/Thelia/Model/Tax.php b/core/lib/Thelia/Model/Tax.php
index 58144d551..738f16508 100755
--- a/core/lib/Thelia/Model/Tax.php
+++ b/core/lib/Thelia/Model/Tax.php
@@ -2,7 +2,6 @@
 
 namespace Thelia\Model;
 
-use Symfony\Component\Form\Exception\Exception;
 use Thelia\Exception\TaxEngineException;
 use Thelia\Model\Base\Tax as BaseTax;
 use Thelia\TaxEngine\TaxType\BaseTaxType;
@@ -49,7 +48,7 @@ class Tax extends BaseTax
         if(!$instance instanceof BaseTaxType) {
             throw new TaxEngineException('Recorded type does not extends BaseTaxType', TaxEngineException::BAD_RECORDED_TYPE);
         }
-        
+
         return $instance;
     }
 
diff --git a/core/lib/Thelia/Model/TaxRuleQuery.php b/core/lib/Thelia/Model/TaxRuleQuery.php
index 75a21a453..d5ce47546 100755
--- a/core/lib/Thelia/Model/TaxRuleQuery.php
+++ b/core/lib/Thelia/Model/TaxRuleQuery.php
@@ -21,7 +21,7 @@ class TaxRuleQuery extends BaseTaxRuleQuery
 {
     const ALIAS_FOR_TAX_RULE_COUNTRY_POSITION = 'taxRuleCountryPosition';
 
-    public function getTaxCalculatorGroupedCollection(Product $product, Country $country)
+    public function getTaxCalculatorCollection(Product $product, Country $country)
     {
         $search = TaxQuery::create()
             ->filterByTaxRuleCountry(
diff --git a/core/lib/Thelia/TaxEngine/Calculator.php b/core/lib/Thelia/TaxEngine/Calculator.php
index 1630ad550..2708e88c6 100755
--- a/core/lib/Thelia/TaxEngine/Calculator.php
+++ b/core/lib/Thelia/TaxEngine/Calculator.php
@@ -34,6 +34,9 @@ use Thelia\Model\TaxRuleQuery;
  */
 class Calculator
 {
+    /**
+     * @var TaxRuleQuery
+     */
     protected $taxRuleQuery = null;
 
     protected $taxRulesCollection = null;
@@ -62,7 +65,7 @@ class Calculator
         $this->product = $product;
         $this->country = $country;
 
-        $this->taxRulesCollection = $this->taxRuleQuery->getTaxCalculatorGroupedCollection($product, $country);
+        $this->taxRulesCollection = $this->taxRuleQuery->getTaxCalculatorCollection($product, $country);
 
         return $this;
     }
diff --git a/core/lib/Thelia/TaxEngine/TaxType/BaseTaxType.php b/core/lib/Thelia/TaxEngine/TaxType/BaseTaxType.php
index d155bb4c0..7f487bf64 100755
--- a/core/lib/Thelia/TaxEngine/TaxType/BaseTaxType.php
+++ b/core/lib/Thelia/TaxEngine/TaxType/BaseTaxType.php
@@ -22,6 +22,7 @@
 /*************************************************************************************/
 namespace Thelia\TaxEngine\TaxType;
 
+use Thelia\Exception\TaxEngineException;
 use Thelia\Type\TypeInterface;
 
 /**
@@ -42,24 +43,20 @@ abstract class BaseTaxType
         $this->requirements = $this->getRequirementsList();
 
         if(!is_array($this->requirements)) {
-            //@todo throw sg
-            exit('err_1');
+            throw new TaxEngineException('getRequirementsList must return an array', TaxEngineException::TAX_TYPE_BAD_ABSTRACT_METHOD);
         }
 
         foreach($this->requirements as $requirement => $requirementType) {
             if(!$requirementType instanceof TypeInterface) {
-                //@todo throw sg
-                exit('err_2');
+                throw new TaxEngineException('getRequirementsList must return an array of TypeInterface', TaxEngineException::TAX_TYPE_BAD_ABSTRACT_METHOD);
             }
 
             if(!array_key_exists($requirement, $requirementsValues)) {
-                //@todo throw sg
-                exit('err_3');
+                throw new TaxEngineException('Cannot load requirements : requirement value for `' . $requirement . '` not found', TaxEngineException::TAX_TYPE_REQUIREMENT_NOT_FOUND);
             }
 
             if(!$requirementType->isValid($requirementsValues[$requirement])) {
-                //@todo throw sg
-                exit('err_4');
+                throw new TaxEngineException('Requirement value for `' . $requirement . '` does not match required type', TaxEngineException::TAX_TYPE_BAD_REQUIREMENT_VALUE);
             }
 
             $this->requirements[$requirement] = $requirementsValues[$requirement];
@@ -69,13 +66,11 @@ abstract class BaseTaxType
     public function getRequirement($key)
     {
         if($this->requirements === null) {
-            //@todo throw sg
-            exit('err_5');
+            throw new TaxEngineException('Requirements are empty in BaseTaxType::getRequirement', TaxEngineException::UNDEFINED_REQUIREMENTS);
         }
 
         if(!array_key_exists($key, $this->requirements)) {
-            //@todo throw sg
-            exit('err_6');
+            throw new TaxEngineException('Requirement value for `' . $key . '` does not exists in BaseTaxType::$requirements', TaxEngineException::UNDEFINED_REQUIREMENT_VALUE);
         }
 
         return $this->requirements[$key];
diff --git a/core/lib/Thelia/Tests/TaxEngine/CalculatorTest.php b/core/lib/Thelia/Tests/TaxEngine/CalculatorTest.php
index fac6ca643..719d90835 100755
--- a/core/lib/Thelia/Tests/TaxEngine/CalculatorTest.php
+++ b/core/lib/Thelia/Tests/TaxEngine/CalculatorTest.php
@@ -83,9 +83,9 @@ class CalculatorTest extends \PHPUnit_Framework_TestCase
 
         $calculator = new Calculator();
 
-        $taxRuleQuery = $this->getMock('\Thelia\Model\TaxRuleQuery', array('getTaxCalculatorGroupedCollection'));
+        $taxRuleQuery = $this->getMock('\Thelia\Model\TaxRuleQuery', array('getTaxCalculatorCollection'));
         $taxRuleQuery->expects($this->once())
-            ->method('getTaxCalculatorGroupedCollection')
+            ->method('getTaxCalculatorCollection')
             ->with($productQuery, $countryQuery)
             ->will($this->returnValue('foo'));
 
@@ -104,7 +104,7 @@ class CalculatorTest extends \PHPUnit_Framework_TestCase
         );
         $this->assertEquals(
             'foo',
-            $this->getProperty('taxRulesGroupedCollection')->getValue($calculator)
+            $this->getProperty('taxRulesCollection')->getValue($calculator)
         );
     }
 
@@ -124,35 +124,37 @@ class CalculatorTest extends \PHPUnit_Framework_TestCase
      */
     public function testGetTaxAmountBadAmount()
     {
-        $taxRulesGroupedCollection = new ObjectCollection();
+        $taxRulesCollection = new ObjectCollection();
 
         $calculator = new Calculator();
 
-        $rewritingUrlQuery = $this->getProperty('taxRulesGroupedCollection');
-        $rewritingUrlQuery->setValue($calculator, $taxRulesGroupedCollection);
+        $rewritingUrlQuery = $this->getProperty('taxRulesCollection');
+        $rewritingUrlQuery->setValue($calculator, $taxRulesCollection);
 
         $calculator->getTaxAmount('foo');
     }
 
     public function testGetTaxAmountAndGetTaxedPrice()
     {
-        $taxRulesGroupedCollection = new ObjectCollection();
-        $taxRulesGroupedCollection->setModel('\Thelia\Model\Tax');
+        $taxRulesCollection = new ObjectCollection();
+        $taxRulesCollection->setModel('\Thelia\Model\Tax');
 
         $tax = new Tax();
-        $tax->setVirtualColumn('taxRateSum', 10);
+        $tax->setType('PricePercentTaxType')
+            ->setRequirements(array('percent' => 10));
 
-        $taxRulesGroupedCollection->append($tax);
+        $taxRulesCollection->append($tax);
 
         $tax = new Tax();
-        $tax->setVirtualColumn('taxRateSum', 8);
+        $tax->setType('PricePercentTaxType')
+            ->setRequirements(array('percent' => 8));
 
-        $taxRulesGroupedCollection->append($tax);
+        $taxRulesCollection->append($tax);
 
         $calculator = new Calculator();
 
-        $rewritingUrlQuery = $this->getProperty('taxRulesGroupedCollection');
-        $rewritingUrlQuery->setValue($calculator, $taxRulesGroupedCollection);
+        $rewritingUrlQuery = $this->getProperty('taxRulesCollection');
+        $rewritingUrlQuery->setValue($calculator, $taxRulesCollection);
 
         $taxAmount = $calculator->getTaxAmount(500);
         $taxedPrice = $calculator->getTaxedPrice(500);