diff --git a/htdocs/core/class/html.form.class.php b/htdocs/core/class/html.form.class.php
index 95af5d1ff25..15646307c91 100644
--- a/htdocs/core/class/html.form.class.php
+++ b/htdocs/core/class/html.form.class.php
@@ -3096,10 +3096,20 @@ class Form
         		$defaulttx = $this->cache_vatrates[$num-1]['txtva'];
         	}
 
-        	if (! $options_only) $return.= '<select class="flat" id="'.$htmlname.'" name="'.$htmlname.'">';
+        	// Disabled if customer is not subject to VAT
+        	$disabled=false;
+        	if (is_object($societe_acheteuse) && ! empty($societe_acheteuse->id)
+        		&& $societe_acheteuse->tva_assuj == "0") {
+        		$disabled=true;
+        	}
+
+        	if (! $options_only) $return.= '<select class="flat" id="'.$htmlname.'" name="'.$htmlname.'"'.($disabled?' disabled="disabled"':'').'>';
 
         	foreach ($this->cache_vatrates as $rate)
         	{
+        		// Force 0 if customer is not subject to VAT
+        		if ($disabled && $rate['txtva'] != 0) continue;
+
         		$return.= '<option value="'.$rate['txtva'];
         		$return.= $rate['nprtva'] ? '*': '';
         		$return.= '"';
diff --git a/htdocs/core/tpl/objectline_add.tpl.php b/htdocs/core/tpl/objectline_add.tpl.php
index 817878ee3ba..473b8589a58 100644
--- a/htdocs/core/tpl/objectline_add.tpl.php
+++ b/htdocs/core/tpl/objectline_add.tpl.php
@@ -146,8 +146,7 @@ if (! empty($conf->margin->enabled)) {
 
 	<td align="right">
 	<?php
-	if ($buyer->tva_assuj == "0") echo '<input type="hidden" name="tva_tx" value="0">0';
-	else echo $form->load_tva('tva_tx', (GETPOST('tva_tx')?GETPOST('tva_tx'):-1), $seller, $buyer);
+	echo $form->load_tva('tva_tx', (GETPOST('tva_tx')?GETPOST('tva_tx'):-1), $seller, $buyer);
 	?>
 	<input type="hidden" id="origin_tva_tx_cache" name="origin_tva_tx_cache" value="" />
 	</td>