diff --git a/htdocs/core/lib/tax.lib.php b/htdocs/core/lib/tax.lib.php
index 399983dbd16..884ff4fc922 100644
--- a/htdocs/core/lib/tax.lib.php
+++ b/htdocs/core/lib/tax.lib.php
@@ -86,7 +86,7 @@ function tax_prepare_head(ChargeSociales $object)
  *  @param  string	$direction   	'sell' or 'buy'
  *  @param  int		$m				Month
  *  @param  int		$q           	Quarter
- *  @return array       			Array with details of VATs (per third parties), -1 if no accountancy module, -2 if not yet developped, -3 if error
+ *  @return array|int               Array with details of VATs (per third parties), -1 if no accountancy module, -2 if not yet developped, -3 if error
  */
 function tax_by_thirdparty($type, $db, $y, $date_start, $date_end, $modetax, $direction, $m = 0, $q = 0)
 {
@@ -111,7 +111,7 @@ function tax_by_thirdparty($type, $db, $y, $date_start, $date_end, $modetax, $di
     	$paymentfacturetable='paiement_facture';
     	$invoicefieldref='ref';
     }
-    if ($direction == 'buy')
+    elseif ($direction == 'buy')
     {
     	$invoicetable='facture_fourn';
     	$invoicedettable='facture_fourn_det';
@@ -554,7 +554,7 @@ function tax_by_thirdparty($type, $db, $y, $date_start, $date_end, $modetax, $di
  *  @param  int		$modetax     	Not used
  *  @param  int		$direction   	'sell' (customer invoice) or 'buy' (supplier invoices)
  *  @param  int		$m           	Month
- *  @return array       			Array with details of VATs (per rate), -1 if no accountancy module, -2 if not yet developped, -3 if error
+ *  @return array|int               Array with details of VATs (per rate), -1 if no accountancy module, -2 if not yet developped, -3 if error
  */
 function tax_by_rate($type, $db, $y, $q, $date_start, $date_end, $modetax, $direction, $m = 0)
 {