diff --git a/vendor/magento/module-sales-rule/Helper/CartFixedDiscount.php b/vendor/magento/module-sales-rule/Helper/CartFixedDiscount.php
index e3ad412a8e7..eeab18e9c36 100644
--- a/vendor/magento/module-sales-rule/Helper/CartFixedDiscount.php
+++ b/vendor/magento/module-sales-rule/Helper/CartFixedDiscount.php
@@ -7,11 +7,14 @@ declare(strict_types=1);
 
 namespace Magento\SalesRule\Helper;
 
+use Magento\Framework\App\Config\ScopeConfigInterface;
 use Magento\Framework\Pricing\PriceCurrencyInterface;
 use Magento\Quote\Api\Data\AddressInterface;
+use Magento\Quote\Model\Cart\ShippingMethodConverter;
 use Magento\Quote\Model\Quote;
 use Magento\SalesRule\Model\DeltaPriceRound;
 use Magento\SalesRule\Model\Rule;
+use Magento\Store\Model\ScopeInterface;
 
 /**
  * Helper for CartFixed Available Discount and Quote Totals
@@ -28,28 +31,45 @@ class CartFixedDiscount
      */
     private $priceCurrency;
 
+    /**
+     * @var ShippingMethodConverter
+     */
+    private $shippingMethodConverter = null;
+
+    /**
+     * @var ScopeConfigInterface
+     */
+    private $scopeConfig = null;
+
     /**
      * @param DeltaPriceRound $deltaPriceRound
      * @param PriceCurrencyInterface $priceCurrency
+     * @param ShippingMethodConverter $shippingMethodConverter
+     * @param ScopeConfigInterface $scopeConfig
      */
     public function __construct(
         DeltaPriceRound $deltaPriceRound,
-        PriceCurrencyInterface $priceCurrency
+        PriceCurrencyInterface $priceCurrency,
+        ShippingMethodConverter $shippingMethodConverter,
+        ScopeConfigInterface $scopeConfig
     ) {
         $this->deltaPriceRound = $deltaPriceRound;
         $this->priceCurrency = $priceCurrency;
+        $this->shippingMethodConverter = $shippingMethodConverter;
+        $this->scopeConfig = $scopeConfig;
     }
 
     /**
      * Retrieve shipping amount by quote address and shipping method
      *
      * @param AddressInterface $address
+     * @param float $shippingAmount
      * @return float
      */
     public function calculateShippingAmountWhenAppliedToShipping(
-        AddressInterface $address
+        AddressInterface $address,
+        float $shippingAmount
     ): float {
-        $shippingAmount = (float) $address->getShippingAmount();
         if ($shippingAmount == 0.0) {
             $addressQty = $this->getAddressQty($address);
             $address->setItemQty($addressQty);
@@ -59,11 +79,16 @@ class CartFixedDiscount
             foreach ($shippingRates as $shippingRate) {
                 if ($shippingRate->getCode() === $address->getShippingMethod()
                 ) {
-                    $shippingAmount = (float) $shippingRate->getPrice();
+                    $shippingMethod = $this->shippingMethodConverter
+                        ->modelToDataObject($shippingRate, $address->getQuote()->getQuoteCurrencyCode());
+                    $shippingAmount = $this->applyDiscountOnPricesIncludedTax()
+                        ? $shippingMethod->getPriceInclTax()
+                        : $shippingMethod->getPriceExclTax();
                     break;
                 }
             }
         }
+
         return $shippingAmount;
     }
 
@@ -180,14 +205,17 @@ class CartFixedDiscount
      *
      * @param Quote\Address $address
      * @param float $baseRuleTotals
+     * @param float $shippingAmount
      * @return float
      */
     public function getQuoteTotalsForRegularShipping(
         Quote\Address $address,
-        float $baseRuleTotals
+        float $baseRuleTotals,
+        float $shippingAmount
     ): float {
         $baseRuleTotals += $this->calculateShippingAmountWhenAppliedToShipping(
-            $address
+            $address,
+            $shippingAmount
         );
         return $baseRuleTotals;
     }
@@ -200,6 +228,7 @@ class CartFixedDiscount
      * @param bool $isMultiShipping
      * @param Quote\Address $address
      * @param float $baseRuleTotals
+     * @param float $shippingAmount
      * @return float
      */
     public function getBaseRuleTotals(
@@ -207,12 +236,13 @@ class CartFixedDiscount
         Quote $quote,
         bool $isMultiShipping,
         Quote\Address $address,
-        float $baseRuleTotals
+        float $baseRuleTotals,
+        float $shippingAmount
     ): float {
         if ($isAppliedToShipping) {
             $baseRuleTotals = ($quote->getIsMultiShipping() && $isMultiShipping) ?
                 $this->getQuoteTotalsForMultiShipping($quote) :
-                $this->getQuoteTotalsForRegularShipping($address, $baseRuleTotals);
+                $this->getQuoteTotalsForRegularShipping($address, $baseRuleTotals, $shippingAmount);
         }
         return (float) $baseRuleTotals;
     }
@@ -244,6 +274,19 @@ class CartFixedDiscount
         return $availableDiscountAmount;
     }
 
+    /**
+     * Get configuration setting "Apply Discount On Prices Including Tax" value
+     *
+     * @return bool
+     */
+    public function applyDiscountOnPricesIncludedTax(): bool
+    {
+        return (bool) $this->scopeConfig->getValue(
+            'tax/calculation/discount_tax',
+            ScopeInterface::SCOPE_STORE
+        ) ?? false;
+    }
+
     /**
      * Get address quantity.
      *
diff --git a/vendor/magento/module-sales-rule/Model/Rule/Action/Discount/CartFixed.php b/vendor/magento/module-sales-rule/Model/Rule/Action/Discount/CartFixed.php
index 9794dc1628d..2f9dbb9faea 100644
--- a/vendor/magento/module-sales-rule/Model/Rule/Action/Discount/CartFixed.php
+++ b/vendor/magento/module-sales-rule/Model/Rule/Action/Discount/CartFixed.php
@@ -70,6 +70,7 @@ class CartFixed extends AbstractDiscount
      * @return Data
      * @throws LocalizedException
      * @SuppressWarnings(PHPMD.CyclomaticComplexity)
+     * @SuppressWarnings(PHPMD.NPathComplexity)
      * @SuppressWarnings(PHPMD.ExcessiveMethodLength)
      */
     public function calculate($rule, $item, $qty)
@@ -104,6 +105,9 @@ class CartFixed extends AbstractDiscount
 
         if ($availableDiscountAmount > 0) {
             $store = $quote->getStore();
+            $shippingPrice = $this->cartFixedDiscountHelper->applyDiscountOnPricesIncludedTax()
+                ? (float) $address->getShippingInclTax()
+                : (float) $address->getShippingExclTax();
             $baseRuleTotals = $shippingMethod ?
                 $this->cartFixedDiscountHelper
                     ->getBaseRuleTotals(
@@ -111,7 +115,8 @@ class CartFixed extends AbstractDiscount
                         $quote,
                         $isMultiShipping,
                         $address,
-                        $baseRuleTotals
+                        $baseRuleTotals,
+                        $shippingPrice
                     ) : $baseRuleTotals;
             if ($isAppliedToShipping) {
                 $baseDiscountAmount = $this->cartFixedDiscountHelper
diff --git a/vendor/magento/module-sales-rule/Model/Validator.php b/vendor/magento/module-sales-rule/Model/Validator.php
index 26fb7ee7217..4c55f9c0dd2 100644
--- a/vendor/magento/module-sales-rule/Model/Validator.php
+++ b/vendor/magento/module-sales-rule/Model/Validator.php
@@ -370,7 +370,8 @@ class Validator extends \Magento\Framework\Model\AbstractModel
                         $cartRules[$rule->getId()] = $rule->getDiscountAmount();
                     }
                     if ($cartRules[$rule->getId()] > 0) {
-                        $shippingAmount = $address->getShippingAmount() - $address->getShippingDiscountAmount();
+                        $shippingQuoteAmount = (float) $address->getShippingAmount()
+                            - (float) $address->getShippingDiscountAmount();
                         $quoteBaseSubtotal = (float) $quote->getBaseSubtotal();
                         $isMultiShipping = $this->cartFixedDiscountHelper->checkMultiShippingQuote($quote);
                         if ($isAppliedToShipping) {
@@ -378,17 +379,18 @@ class Validator extends \Magento\Framework\Model\AbstractModel
                                 $this->cartFixedDiscountHelper->getQuoteTotalsForMultiShipping($quote) :
                                 $this->cartFixedDiscountHelper->getQuoteTotalsForRegularShipping(
                                     $address,
-                                    $quoteBaseSubtotal
+                                    $quoteBaseSubtotal,
+                                    $shippingQuoteAmount
                                 );
                             $discountAmount = $this->cartFixedDiscountHelper->
                             getShippingDiscountAmount(
                                 $rule,
-                                $shippingAmount,
+                                $shippingQuoteAmount,
                                 $quoteBaseSubtotal
                             );
                             $baseDiscountAmount = $discountAmount;
                         } else {
-                            $discountAmount = min($shippingAmount, $quoteAmount);
+                            $discountAmount = min($shippingQuoteAmount, $quoteAmount);
                             $baseDiscountAmount = min(
                                 $baseShippingAmount - $address->getBaseShippingDiscountAmount(),
                                 $cartRules[$rule->getId()]