diff --git a/includes/abstracts/abstract-wc-order.php b/includes/abstracts/abstract-wc-order.php
index a9e77d0c16e..71ec1b30703 100644
--- a/includes/abstracts/abstract-wc-order.php
+++ b/includes/abstracts/abstract-wc-order.php
@@ -992,8 +992,8 @@ abstract class WC_Abstract_Order extends WC_Abstract_Legacy_Order {
 		$found_tax_classes = array();
 
 		foreach ( $this->get_items() as $item ) {
-			if ( $_product = $item->get_product() ) {
-				$found_tax_classes[] = $_product->get_tax_class();
+			if ( ( $product = $item->get_product() ) && ( $product->is_taxable() || $product->is_shipping_taxable() ) ) {
+				$found_tax_classes[] = $product->get_tax_class();
 			}
 		}
 
diff --git a/includes/class-wc-cart.php b/includes/class-wc-cart.php
index e0edaa7cc3f..dfcfcb22f27 100644
--- a/includes/class-wc-cart.php
+++ b/includes/class-wc-cart.php
@@ -775,7 +775,9 @@ class WC_Cart {
 		$found_tax_classes = array();
 
 		foreach ( WC()->cart->get_cart() as $item ) {
-			$found_tax_classes[] = $item['data']->get_tax_class();
+			if ( $item['data'] && ( $item['data']->is_taxable() || $item['data']->is_shipping_taxable() ) ) {
+				$found_tax_classes[] = $item['data']->get_tax_class();
+			}
 		}
 
 		return array_unique( $found_tax_classes );
diff --git a/includes/class-wc-tax.php b/includes/class-wc-tax.php
index a0c72452db3..e458dc68ee3 100644
--- a/includes/class-wc-tax.php
+++ b/includes/class-wc-tax.php
@@ -558,6 +558,11 @@ class WC_Tax {
 				// This will be per order shipping - loop through the order and find the highest tax class rate
 				$cart_tax_classes = WC()->cart->get_cart_item_tax_classes();
 
+				// No tax classes = no taxable items.
+				if ( empty( $cart_tax_classes ) ) {
+					return array();
+				}
+
 				// If multiple classes are found, use the first one found unless a standard rate item is found. This will be the first listed in the 'additional tax class' section.
 				if ( sizeof( $cart_tax_classes ) > 1 && ! in_array( '', $cart_tax_classes ) ) {
 					$tax_classes = self::get_tax_class_slugs();