diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index 3d8fdf6be94..efd73f4bcde 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -3115,53 +3115,80 @@ abstract class CommonObject
 
 			// calcul des marges
 			if (isset($line->fk_remise_except) && isset($conf->global->MARGIN_METHODE_FOR_DISCOUNT)) {    // remise
+			    $pa = $line->qty * $line->pa_ht;
+			    $pv = $line->qty * $line->subprice * (1 - $line->remise_percent / 100);
 				if ($conf->global->MARGIN_METHODE_FOR_DISCOUNT == '1') { // remise globale considérée comme produit
-					$marginInfos['pa_products'] += $line->pa_ht;// ($line->pa_ht != 0)?$line->pa_ht:$line->subprice * (1 - $line->remise_percent / 100);
-					$marginInfos['pv_products'] += $line->subprice * (1 - $line->remise_percent / 100);
-					$marginInfos['pa_total'] +=  $line->pa_ht;// ($line->pa_ht != 0)?$line->pa_ht:$line->subprice * (1 - $line->remise_percent / 100);
-					$marginInfos['pv_total'] +=  $line->subprice * (1 - $line->remise_percent / 100);
+					$marginInfos['pa_products'] += $pa;
+					$marginInfos['pv_products'] += $pv;
+					$marginInfos['pa_total'] +=  $pa;
+					$marginInfos['pv_total'] +=  $pv;
+					// if credit note, margin = -1 * (abs(selling_price) - buying_price)
+					if ($pv < 0)
+						$marginInfos['margin_on_products'] += -1 * (abs($pv) - $pa);
+					else
+						$marginInfos['margin_on_products'] += $pv - $pa;
 				}
 				elseif ($conf->global->MARGIN_METHODE_FOR_DISCOUNT == '2') { // remise globale considérée comme service
-					$marginInfos['pa_services'] += $line->pa_ht;// ($line->pa_ht != 0)?$line->pa_ht:$line->subprice * (1 - $line->remise_percent / 100);
-					$marginInfos['pv_services'] += $line->subprice * (1 - ($line->remise_percent / 100));
-					$marginInfos['pa_total'] +=  $line->pa_ht;// ($line->pa_ht != 0)?$line->pa_ht:$line->subprice * (1 - $line->remise_percent / 100);
-					$marginInfos['pv_total'] +=  $line->subprice * (1 - $line->remise_percent / 100);
+					$marginInfos['pa_services'] += $pa;
+					$marginInfos['pv_services'] += $pv;
+					$marginInfos['pa_total'] +=  $pa;
+					$marginInfos['pv_total'] +=  $pv;
+					// if credit note, margin = -1 * (abs(selling_price) - buying_price)
+					if ($pv < 0)
+						$marginInfos['margin_on_services'] += -1 * (abs($pv) - $pa);
+					else
+						$marginInfos['margin_on_services'] += $pv - $pa;
 				}
 				elseif ($conf->global->MARGIN_METHODE_FOR_DISCOUNT == '3') { // remise globale prise en compte uniqt sur total
-					$marginInfos['pa_total'] += $line->pa_ht;// ($line->pa_ht != 0)?$line->pa_ht:$line->subprice * (1 - $line->remise_percent / 100);
-					$marginInfos['pv_total'] += $line->subprice * (1 - ($line->remise_percent / 100));
+					$marginInfos['pa_total'] += $pa;
+					$marginInfos['pv_total'] += $pv;
 				}
 			}
 			else {
 				$type=$line->product_type?$line->product_type:$line->fk_product_type;
 				if ($type == 0) {  // product
-					$marginInfos['pa_products'] += $line->qty * $line->pa_ht;
-					$marginInfos['pv_products'] += $line->qty * $line->subprice * (1 - $line->remise_percent / 100);
-					$marginInfos['pa_total'] +=  $line->qty * $line->pa_ht;
-					$marginInfos['pv_total'] +=  $line->qty * $line->subprice * (1 - $line->remise_percent / 100);
+				    $pa = $line->qty * $line->pa_ht;
+				    $pv = $line->qty * $line->subprice * (1 - $line->remise_percent / 100);
+					$marginInfos['pa_products'] += $pa;
+					$marginInfos['pv_products'] += $pv;
+					$marginInfos['pa_total'] +=  $pa;
+					$marginInfos['pv_total'] +=  $pv;
+					// if credit note, margin = -1 * (abs(selling_price) - buying_price)
+					if ($pv < 0)
+						$marginInfos['margin_on_products'] += -1 * (abs($pv) - $pa);
+					else
+						$marginInfos['margin_on_products'] += $pv - $pa;
 				}
 				elseif ($type == 1) {  // service
-					$marginInfos['pa_services'] += $line->qty * $line->pa_ht;
-					$marginInfos['pv_services'] += $line->qty * $line->subprice * (1 - ($line->remise_percent / 100));
-					$marginInfos['pa_total'] +=  $line->qty * $line->pa_ht;
-					$marginInfos['pv_total'] +=  $line->qty * $line->subprice * (1 - $line->remise_percent / 100);
+				    $pa = $line->qty * $line->pa_ht;
+				    $pv = $line->qty * $line->subprice * (1 - $line->remise_percent / 100);
+					$marginInfos['pa_services'] += $pa;
+					$marginInfos['pv_services'] += $pv;
+					$marginInfos['pa_total'] +=  $pa;
+					$marginInfos['pv_total'] +=  $pv;
+					// if credit note, margin = -1 * (abs(selling_price) - buying_price)
+					if ($pv < 0)
+						$marginInfos['margin_on_services'] += -1 * (abs($pv) - $pa);
+					else
+						$marginInfos['margin_on_services'] += $pv - $pa;
 				}
 			}
 		}
-
-		$marginInfos['margin_on_products'] = $marginInfos['pv_products'] - $marginInfos['pa_products'];
 		if ($marginInfos['pa_products'] > 0)
 			$marginInfos['margin_rate_products'] = 100 * round($marginInfos['margin_on_products'] / $marginInfos['pa_products'],5);
 		if ($marginInfos['pv_products'] > 0)
 			$marginInfos['mark_rate_products'] = 100 * round($marginInfos['margin_on_products'] / $marginInfos['pv_products'],5);
 
-		$marginInfos['margin_on_services'] = $marginInfos['pv_services'] - $marginInfos['pa_services'];
 		if ($marginInfos['pa_services'] > 0)
 			$marginInfos['margin_rate_services'] = 100 * round($marginInfos['margin_on_services'] / $marginInfos['pa_services'],5);
 		if ($marginInfos['pv_services'] > 0)
 			$marginInfos['mark_rate_services'] = 100 * round($marginInfos['margin_on_services'] / $marginInfos['pv_services'],5);
 
-		$marginInfos['total_margin'] = $marginInfos['pv_total'] - $marginInfos['pa_total'];
+		// if credit note, margin = -1 * (abs(selling_price) - buying_price)
+		if ($marginInfos['pv_total'] < 0)
+			$marginInfos['total_margin'] = -1 * (abs($marginInfos['pv_total']) - $marginInfos['pa_total']);
+		else
+			$marginInfos['total_margin'] = $marginInfos['pv_total'] - $marginInfos['pa_total'];
 		if ($marginInfos['pa_total'] > 0)
 			$marginInfos['total_margin_rate'] = 100 * round($marginInfos['total_margin'] / $marginInfos['pa_total'],5);
 		if ($marginInfos['pv_total'] > 0)