--- uc_vat.module (saved version)
+++ (current document)
@@ -884,7 +884,7 @@
       // Special handling for modules that provide their own tax adjustments.
       $callback = _line_item_data($line_item['type'], 'tax_adjustment');
       if ($callback && function_exists($callback)) {
-      	$taxable_amount += $callback($line_item['amount'], $order, $tax) / $tax->rate;
+        if ($tax->rate > 0) $taxable_amount += $callback($line_item['amount'], $order, $tax) / $tax->rate;
         continue;
       }