diff --git a/vendor/magento/module-customer-custom-attributes/Block/Checkout/AttributeMerger.php b/vendor/magento/module-customer-custom-attributes/Block/Checkout/AttributeMerger.php
index 69c4572a749..160cd621340 100644
--- a/vendor/magento/module-customer-custom-attributes/Block/Checkout/AttributeMerger.php
+++ b/vendor/magento/module-customer-custom-attributes/Block/Checkout/AttributeMerger.php
@@ -104,7 +104,7 @@ class AttributeMerger extends CheckoutAttributesMerger
 
         $providerName = $result['provider'];
 
-        if ($attributeConfig['formElement'] === 'select') {
+        if (in_array($attributeConfig['formElement'], ['select', 'multiselect'])) {
             $result['deps'] = [$providerName];
             $result['exports']['options'] =
                 'index = ' . $providerName . ':customAttributes.' . $attributeCode;
diff --git a/vendor/magento/module-customer-custom-attributes/Block/Checkout/LayoutProcessor.php b/vendor/magento/module-customer-custom-attributes/Block/Checkout/LayoutProcessor.php
index f952e2de470..71bcbda0662 100644
--- a/vendor/magento/module-customer-custom-attributes/Block/Checkout/LayoutProcessor.php
+++ b/vendor/magento/module-customer-custom-attributes/Block/Checkout/LayoutProcessor.php
@@ -5,27 +5,32 @@
  */
 namespace Magento\CustomerCustomAttributes\Block\Checkout;
 
+use Magento\Checkout\Block\Checkout\LayoutProcessorInterface;
+use Magento\Customer\Model\AttributeMetadataDataProvider;
 use Magento\Framework\App\Config\ScopeConfigInterface;
 use Magento\Framework\App\ObjectManager;
+use Magento\Framework\Exception\LocalizedException;
 use Magento\Store\Model\ScopeInterface;
+use Magento\Ui\Component\Form\AttributeMapper;
+use Magento\Checkout\Block\Checkout\AttributeMerger as AttributeMergerBlock;
 
 /**
  * Layout processor for checkout with customer address search.
  */
-class LayoutProcessor implements \Magento\Checkout\Block\Checkout\LayoutProcessorInterface
+class LayoutProcessor implements LayoutProcessorInterface
 {
     /**
-     * @var \Magento\Customer\Model\AttributeMetadataDataProvider
+     * @var AttributeMetadataDataProvider
      */
     protected $attributeMetadataDataProvider;
 
     /**
-     * @var \Magento\Ui\Component\Form\AttributeMapper
+     * @var AttributeMapper
      */
     protected $attributeMapper;
 
     /**
-     * @var \Magento\Checkout\Block\Checkout\AttributeMerger
+     * @var AttributeMergerBlock
      */
     protected $merger;
 
@@ -37,15 +42,15 @@ class LayoutProcessor implements \Magento\Checkout\Block\Checkout\LayoutProcesso
     private $scopeConfig;
 
     /**
-     * @param \Magento\Customer\Model\AttributeMetadataDataProvider $attributeMetadataDataProvider
-     * @param \Magento\Ui\Component\Form\AttributeMapper $attributeMapper
-     * @param \Magento\Checkout\Block\Checkout\AttributeMerger $merger
+     * @param AttributeMetadataDataProvider $attributeMetadataDataProvider
+     * @param AttributeMapper $attributeMapper
+     * @param AttributeMergerBlock $merger
      * @param ScopeConfigInterface|null $scopeConfig
      */
     public function __construct(
-        \Magento\Customer\Model\AttributeMetadataDataProvider $attributeMetadataDataProvider,
-        \Magento\Ui\Component\Form\AttributeMapper $attributeMapper,
-        \Magento\Checkout\Block\Checkout\AttributeMerger $merger,
+        AttributeMetadataDataProvider $attributeMetadataDataProvider,
+        AttributeMapper $attributeMapper,
+        AttributeMergerBlock $merger,
         ScopeConfigInterface $scopeConfig = null
     ) {
         $this->attributeMetadataDataProvider = $attributeMetadataDataProvider;
@@ -59,6 +64,7 @@ class LayoutProcessor implements \Magento\Checkout\Block\Checkout\LayoutProcesso
      *
      * @param array $jsLayout
      * @return array
+     * @throws LocalizedException
      */
     public function process($jsLayout)
     {
@@ -79,6 +85,7 @@ class LayoutProcessor implements \Magento\Checkout\Block\Checkout\LayoutProcesso
 
         $jsLayout = $this->processCustomAttributesForPaymentMethods($jsLayout, $addressCustomAttributes);
         $jsLayout = $this->mergeCustomAttributes($jsLayout, $addressCustomAttributes);
+        $jsLayout = $this->mergeCustomAttributesOfBillingAddress($jsLayout, $addressCustomAttributes);
 
         return $jsLayout;
     }
@@ -87,7 +94,7 @@ class LayoutProcessor implements \Magento\Checkout\Block\Checkout\LayoutProcesso
      * Returns a list of custom attributes for customer addresses.
      *
      * @return array
-     * @throws \Magento\Framework\Exception\LocalizedException
+     * @throws LocalizedException
      */
     private function getAddressCustomAttributes()
     {
@@ -165,4 +172,34 @@ class LayoutProcessor implements \Magento\Checkout\Block\Checkout\LayoutProcesso
 
         return $jsLayout;
     }
+
+    /**
+     * Merge custom attributes of billing address.
+     *
+     * @param array $jsLayout
+     * @param array $addressCustomAttributes
+     * @return array
+     */
+    private function mergeCustomAttributesOfBillingAddress(
+        array $jsLayout,
+        array $addressCustomAttributes
+    ): array {
+        if (isset($jsLayout['components']['checkout']['children']['steps']['children']['billing-step']
+            ['children']['payment']['children']['afterMethods']['children']['billing-address-form']
+            ['children']['form-fields'])) {
+            $fields = $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']
+            ['children']['payment']['children']['afterMethods']['children']['billing-address-form']
+            ['children']['form-fields']['children'];
+            $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']
+            ['children']['payment']['children']['afterMethods']['children']['billing-address-form']
+            ['children']['form-fields']['children'] = $this->merger->merge(
+                $addressCustomAttributes,
+                'checkoutProvider',
+                'billingAddressshared.custom_attributes',
+                $fields
+            );
+        }
+
+        return $jsLayout;
+    }
 }
diff --git a/vendor/magento/module-customer-custom-attributes/Model/CustomerAddressCustomAttributesProcessor.php b/vendor/magento/module-customer-custom-attributes/Model/CustomerAddressCustomAttributesProcessor.php
new file mode 100644
index 00000000000..ad03fa75f0b
--- /dev/null
+++ b/vendor/magento/module-customer-custom-attributes/Model/CustomerAddressCustomAttributesProcessor.php
@@ -0,0 +1,38 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\CustomerCustomAttributes\Model;
+
+use Magento\Quote\Api\Data\AddressInterface;
+
+/**
+ * Helper class for processing shipping or billing custom attributes
+ */
+class CustomerAddressCustomAttributesProcessor
+{
+    /**
+     * Process customer custom attribute before save shipping or billing address
+     *
+     * @param AddressInterface $addressInformation
+     * @return void
+     */
+    public function execute(
+        AddressInterface $addressInformation
+    ): void {
+        $customerCustomAttributes = $addressInformation->getCustomAttributes();
+        if ($customerCustomAttributes) {
+            foreach ($customerCustomAttributes as $customAttribute) {
+                $customAttributeValue = $customAttribute->getValue();
+                if ($customAttributeValue && is_array($customAttributeValue)) {
+                    if ($customAttributeValue['value'] !== null) {
+                        $customAttribute->setValue($customAttributeValue['value']);
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessCustomerBillingAddressCustomAttributes.php b/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessCustomerBillingAddressCustomAttributes.php
new file mode 100644
index 00000000000..49e73db5996
--- /dev/null
+++ b/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessCustomerBillingAddressCustomAttributes.php
@@ -0,0 +1,54 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\CustomerCustomAttributes\Model\Plugin;
+
+use Magento\Checkout\Api\PaymentInformationManagementInterface;
+use Magento\CustomerCustomAttributes\Model\CustomerAddressCustomAttributesProcessor;
+use Magento\Quote\Api\Data\AddressInterface;
+use Magento\Quote\Api\Data\PaymentInterface;
+
+/**
+ * Process custom customer attributes before saving billing address
+ */
+class ProcessCustomerBillingAddressCustomAttributes
+{
+    /** @var CustomerAddressCustomAttributesProcessor */
+    private $customerAddressCustomAttributesProcessor;
+
+    /**
+     * Constructor for billing custom attribute for registered user plugin
+     *
+     * @param CustomerAddressCustomAttributesProcessor $customerAddressCustomAttributesProcessor
+     */
+    public function __construct(
+        CustomerAddressCustomAttributesProcessor $customerAddressCustomAttributesProcessor
+    ) {
+        $this->customerAddressCustomAttributesProcessor = $customerAddressCustomAttributesProcessor;
+    }
+
+    /**
+     * Process billing custom attribute before save for registered customer
+     *
+     * @param PaymentInformationManagementInterface $subject
+     * @param string $cartId
+     * @param PaymentInterface $paymentMethod
+     * @param AddressInterface|null $billingAddress
+     * @return void
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function beforeSavePaymentInformation(
+        PaymentInformationManagementInterface $subject,
+        string $cartId,
+        PaymentInterface $paymentMethod,
+        AddressInterface $billingAddress = null
+    ): void {
+        if ($billingAddress) {
+            $this->customerAddressCustomAttributesProcessor->execute($billingAddress);
+        }
+    }
+}
diff --git a/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessCustomerShippingAddressCustomAttributes.php b/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessCustomerShippingAddressCustomAttributes.php
new file mode 100644
index 00000000000..6b7e6f188d3
--- /dev/null
+++ b/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessCustomerShippingAddressCustomAttributes.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\CustomerCustomAttributes\Model\Plugin;
+
+use Magento\Checkout\Api\ShippingInformationManagementInterface;
+use Magento\Checkout\Api\Data\ShippingInformationInterface;
+use Magento\CustomerCustomAttributes\Model\CustomerAddressCustomAttributesProcessor;
+
+/**
+ * Process custom customer attributes before saving shipping address
+ */
+class ProcessCustomerShippingAddressCustomAttributes
+{
+    /** @var CustomerAddressCustomAttributesProcessor */
+    private $customerAddressCustomAttributesProcessor;
+
+    /**
+     * Constructor for shipping custom attribute for registered user plugin
+     *
+     * @param CustomerAddressCustomAttributesProcessor $customerAddressCustomAttributesProcessor
+     */
+    public function __construct(
+        CustomerAddressCustomAttributesProcessor $customerAddressCustomAttributesProcessor
+    ) {
+        $this->customerAddressCustomAttributesProcessor = $customerAddressCustomAttributesProcessor;
+    }
+
+    /**
+     * Process shipping custom attribute before save for registered customer
+     *
+     * @param ShippingInformationManagementInterface $subject
+     * @param string $cartId
+     * @param ShippingInformationInterface $addressInformation
+     * @return void
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function beforeSaveAddressInformation(
+        ShippingInformationManagementInterface $subject,
+        string $cartId,
+        ShippingInformationInterface $addressInformation
+    ): void {
+        $shippingAddress = $addressInformation->getShippingAddress();
+        if ($shippingAddress) {
+            $this->customerAddressCustomAttributesProcessor->execute($shippingAddress);
+        }
+    }
+}
diff --git a/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessGuestBillingAddressCustomAttributes.php b/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessGuestBillingAddressCustomAttributes.php
new file mode 100644
index 00000000000..0ead39b39fe
--- /dev/null
+++ b/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessGuestBillingAddressCustomAttributes.php
@@ -0,0 +1,56 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\CustomerCustomAttributes\Model\Plugin;
+
+use Magento\Checkout\Api\GuestPaymentInformationManagementInterface;
+use Magento\CustomerCustomAttributes\Model\CustomerAddressCustomAttributesProcessor;
+use Magento\Quote\Api\Data\AddressInterface;
+use Magento\Quote\Api\Data\PaymentInterface;
+
+/**
+ * Process custom guest attributes before saving billing address
+ */
+class ProcessGuestBillingAddressCustomAttributes
+{
+    /** @var CustomerAddressCustomAttributesProcessor */
+    private $customerAddressCustomAttributesProcessor;
+
+    /**
+     * Constructor for billing custom attribute for guest user plugin
+     *
+     * @param CustomerAddressCustomAttributesProcessor $customerAddressCustomAttributesProcessor
+     */
+    public function __construct(
+        CustomerAddressCustomAttributesProcessor $customerAddressCustomAttributesProcessor
+    ) {
+        $this->customerAddressCustomAttributesProcessor = $customerAddressCustomAttributesProcessor;
+    }
+
+    /**
+     * Process billing custom attribute before save for guest
+     *
+     * @param GuestPaymentInformationManagementInterface $subject
+     * @param string $cartId
+     * @param string $email
+     * @param PaymentInterface $paymentMethod
+     * @param AddressInterface|null $billingAddress
+     * @return void
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function beforeSavePaymentInformation(
+        GuestPaymentInformationManagementInterface $subject,
+        string $cartId,
+        string $email,
+        PaymentInterface $paymentMethod,
+        AddressInterface $billingAddress = null
+    ): void {
+        if ($billingAddress) {
+            $this->customerAddressCustomAttributesProcessor->execute($billingAddress);
+        }
+    }
+}
diff --git a/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessGuestShippingAddressCustomAttributes.php b/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessGuestShippingAddressCustomAttributes.php
new file mode 100644
index 00000000000..6aacf6bbaa3
--- /dev/null
+++ b/vendor/magento/module-customer-custom-attributes/Model/Plugin/ProcessGuestShippingAddressCustomAttributes.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\CustomerCustomAttributes\Model\Plugin;
+
+use Magento\Checkout\Api\Data\ShippingInformationInterface;
+use Magento\Checkout\Api\GuestShippingInformationManagementInterface;
+use Magento\CustomerCustomAttributes\Model\CustomerAddressCustomAttributesProcessor;
+
+/**
+ * Process shipping custom guest attributes before saving shipping address
+ */
+class ProcessGuestShippingAddressCustomAttributes
+{
+    /** @var CustomerAddressCustomAttributesProcessor */
+    private $customerAddressCustomAttributesProcessor;
+
+    /**
+     * Constructor for shipping custom attribute for guest user plugin
+     *
+     * @param CustomerAddressCustomAttributesProcessor $customerAddressCustomAttributesProcessor
+     */
+    public function __construct(
+        CustomerAddressCustomAttributesProcessor $customerAddressCustomAttributesProcessor
+    ) {
+        $this->customerAddressCustomAttributesProcessor = $customerAddressCustomAttributesProcessor;
+    }
+
+    /**
+     * Process shipping custom attribute before save for guest
+     *
+     * @param GuestShippingInformationManagementInterface $subject
+     * @param string $cartId
+     * @param ShippingInformationInterface $addressInformation
+     * @return void
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function beforeSaveAddressInformation(
+        GuestShippingInformationManagementInterface $subject,
+        string $cartId,
+        ShippingInformationInterface $addressInformation
+    ): void {
+        $shippingAddress = $addressInformation->getShippingAddress();
+        if ($shippingAddress) {
+            $this->customerAddressCustomAttributesProcessor->execute($shippingAddress);
+        }
+    }
+}
diff --git a/vendor/magento/module-customer-custom-attributes/Plugin/ProcessCustomerCustomBooleanAttributeOptions.php b/vendor/magento/module-customer-custom-attributes/Plugin/ProcessCustomerCustomBooleanAttributeOptions.php
new file mode 100644
index 00000000000..172c041dedf
--- /dev/null
+++ b/vendor/magento/module-customer-custom-attributes/Plugin/ProcessCustomerCustomBooleanAttributeOptions.php
@@ -0,0 +1,58 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\CustomerCustomAttributes\Plugin;
+
+use Magento\Customer\Model\Attribute;
+use Magento\Eav\Api\Data\AttributeInterface;
+use Magento\Ui\Component\Form\AttributeMapper;
+
+/**
+ * Class ProcessCustomerCustomBooleanAttributeOptions
+ *
+ * Process customer custom boolean attribute options and change it
+ * to boolean values
+ */
+class ProcessCustomerCustomBooleanAttributeOptions
+{
+    /**
+     * After map custom boolean attributes plugin.
+     *
+     * @param AttributeMapper $attributeMapper
+     * @param array $meta
+     * @param AttributeInterface $attribute
+     * @return array
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function afterMap(
+        AttributeMapper $attributeMapper,
+        array $meta,
+        AttributeInterface $attribute
+    ): array {
+        if ($attribute instanceof Attribute &&
+            $this->isCustomAttributeBoolean($attribute) &&
+            !empty($meta['options'])) {
+            foreach ($meta['options'] as $key => $option) {
+                $meta['options'][$key]['value'] = (bool) $option['value'];
+            }
+        }
+        return $meta;
+    }
+
+    /**
+     * Check if custom attribute is boolean
+     *
+     * @param AttributeInterface $attribute
+     * @return bool
+     */
+    private function isCustomAttributeBoolean(AttributeInterface $attribute): bool
+    {
+        $isBoolean = (int) $attribute->getIsUserDefined() &&
+            $attribute->getFrontendInput() == 'boolean';
+        return (bool) $isBoolean;
+    }
+}
diff --git a/vendor/magento/module-customer-custom-attributes/etc/di.xml b/vendor/magento/module-customer-custom-attributes/etc/di.xml
index 54590b959cd..3402d6fc7e0 100644
--- a/vendor/magento/module-customer-custom-attributes/etc/di.xml
+++ b/vendor/magento/module-customer-custom-attributes/etc/di.xml
@@ -81,4 +81,16 @@
             <argument name="merger" xsi:type="object">Magento\CustomerCustomAttributes\Block\Checkout\AttributeMerger</argument>
         </arguments>
     </type>
+    <type name="Magento\Checkout\Api\PaymentInformationManagementInterface">
+        <plugin name="process_billing_custom_customer_attributes" type="Magento\CustomerCustomAttributes\Model\Plugin\ProcessCustomerBillingAddressCustomAttributes"/>
+    </type>
+    <type name="Magento\Checkout\Api\ShippingInformationManagementInterface">
+        <plugin name="process_shipping_custom_customer_attributes" type="Magento\CustomerCustomAttributes\Model\Plugin\ProcessCustomerShippingAddressCustomAttributes"/>
+    </type>
+    <type name="Magento\Checkout\Api\GuestPaymentInformationManagementInterface">
+        <plugin name="process_billing_custom_guest_attributes" type="Magento\CustomerCustomAttributes\Model\Plugin\ProcessGuestBillingAddressCustomAttributes"/>
+    </type>
+    <type name="Magento\Checkout\Api\GuestShippingInformationManagementInterface">
+        <plugin name="process_shipping_custom_guest_attributes" type="Magento\CustomerCustomAttributes\Model\Plugin\ProcessGuestShippingAddressCustomAttributes"/>
+    </type>
 </config>
diff --git a/vendor/magento/module-customer-custom-attributes/etc/frontend/di.xml b/vendor/magento/module-customer-custom-attributes/etc/frontend/di.xml
index a3e2e5b6684..25700fa429d 100644
--- a/vendor/magento/module-customer-custom-attributes/etc/frontend/di.xml
+++ b/vendor/magento/module-customer-custom-attributes/etc/frontend/di.xml
@@ -13,4 +13,7 @@
             </argument>
         </arguments>
     </type>
+    <type name="Magento\Ui\Component\Form\AttributeMapper">
+        <plugin name="processCustomerCustomBooleanAttributeOptions" type="Magento\CustomerCustomAttributes\Plugin\ProcessCustomerCustomBooleanAttributeOptions"/>
+    </type>
 </config>