diff --git a/includes/admin/settings/class-wc-gzd-settings-tab-taxes.php b/includes/admin/settings/class-wc-gzd-settings-tab-taxes.php
index 827130868..1d7e2f661 100644
--- a/includes/admin/settings/class-wc-gzd-settings-tab-taxes.php
+++ b/includes/admin/settings/class-wc-gzd-settings-tab-taxes.php
@@ -135,7 +135,7 @@ protected function get_additional_costs_settings() {
 				'desc_tip' => true,
 				'id'       => 'woocommerce_gzd_tax_mode_additional_costs',
 				'type'     => 'radio',
-				'default'  => 'split_tax',
+				'default'  => 'main_service',
 				'options'  => array(
 					'none'         => __( 'WooCommerce default', 'woocommerce-germanized' ),
 					'split_tax'    => __( 'Proportionate', 'woocommerce-germanized' ),
diff --git a/includes/class-wc-gzd-coupon-helper.php b/includes/class-wc-gzd-coupon-helper.php
index 579a98a37..fe8974551 100644
--- a/includes/class-wc-gzd-coupon-helper.php
+++ b/includes/class-wc-gzd-coupon-helper.php
@@ -528,7 +528,7 @@ public function fee_is_voucher( $fee ) {
 		} else {
 			$fee_id = isset( $fee->object ) ? $fee->object->id : $fee->id;
 
-			return strstr( $fee_id, 'voucher_' );
+			return strstr( str_replace( '-', '_', $fee_id ), 'voucher_' );
 		}
 	}
 
diff --git a/includes/class-wc-gzd-order-helper.php b/includes/class-wc-gzd-order-helper.php
index 8b5e016b8..2bb5649e4 100644
--- a/includes/class-wc-gzd-order-helper.php
+++ b/includes/class-wc-gzd-order-helper.php
@@ -326,6 +326,28 @@ public function adjust_additional_costs_item_taxes( $item, $calculate_tax_for =
 			return;
 		}
 
+		if ( is_a( $item, 'WC_Order_Item_Fee' ) ) {
+			$fee_props = (object) array(
+				'id'        => '',
+				'name'      => '',
+				'tax_class' => '',
+				'taxable'   => false,
+				'amount'    => 0,
+				'total'     => 0,
+			);
+
+			$fee_props->name      = $item->get_name();
+			$fee_props->tax_class = $item->get_tax_class();
+			$fee_props->taxable   = 'taxable' === $item->get_tax_status();
+			$fee_props->amount    = $item->get_amount();
+			$fee_props->id        = sanitize_title( $fee_props->name );
+			$fee_props->object    = $fee_props;
+
+			if ( ! apply_filters( 'woocommerce_gzd_force_fee_tax_calculation', true, $fee_props ) ) {
+				return;
+			}
+		}
+
 		if ( $order = $item->get_order() ) {
 			$item->delete_meta_data( '_split_taxes' );
 			$item->delete_meta_data( '_tax_shares' );
diff --git a/includes/wc-gzd-core-functions.php b/includes/wc-gzd-core-functions.php
index 40a0aefce..f26ecb5d7 100644
--- a/includes/wc-gzd-core-functions.php
+++ b/includes/wc-gzd-core-functions.php
@@ -1304,7 +1304,7 @@ function wc_gzd_format_unit_price( $price, $unit, $unit_base, $product_units = '
 }
 
 function wc_gzd_get_additional_costs_tax_calculation_mode() {
-	$value = get_option( 'woocommerce_gzd_tax_mode_additional_costs', 'split_tax' );
+	$value = get_option( 'woocommerce_gzd_tax_mode_additional_costs', 'main_service' );
 
 	if ( ! in_array( $value, array( 'none', 'split_tax', 'main_service' ), true ) ) {
 		$value = 'none';
diff --git a/tests/framework/helpers/class-wc-gzd-helper-order.php b/tests/framework/helpers/class-wc-gzd-helper-order.php
index d40959bb2..9030dbe7f 100644
--- a/tests/framework/helpers/class-wc-gzd-helper-order.php
+++ b/tests/framework/helpers/class-wc-gzd-helper-order.php
@@ -69,7 +69,7 @@ public static function create_billing_order( $incl_tax = true, $items = array(),
 				$item->set_props(
 					array(
 						'method_title' => 'shipping',
-						'total'        => 8.403361,
+						'total'        => 10.0, // Germanized, by default, treats those as gross
 					)
 				);
 			} else {