diff --git a/includes/class-wc-ajax.php b/includes/class-wc-ajax.php
index 71373dc820c..11a618a25fa 100644
--- a/includes/class-wc-ajax.php
+++ b/includes/class-wc-ajax.php
@@ -1372,7 +1372,7 @@ class WC_AJAX {
 				$line_items[ $item_id ]['refund_total'] = wc_format_decimal( $total );
 			}
 			foreach ( $line_item_tax_totals as $item_id => $tax_totals ) {
-				$line_items[ $item_id ]['refund_tax'] = array_map( 'wc_format_decimal', $tax_totals );
+				$line_items[ $item_id ]['refund_tax'] = array_filter( array_map( 'wc_format_decimal', $tax_totals ) );
 			}
 
 			// Create the refund object.