diff --git a/dev/tests/api-functional/testsuite/Magento/Quote/Api/GuestShipmentEstimationWithExtensionAttributesTest.php b/dev/tests/api-functional/testsuite/Magento/Quote/Api/GuestShipmentEstimationWithExtensionAttributesTest.php
new file mode 100644
index 0000000000000..dc59a571aa136
--- /dev/null
+++ b/dev/tests/api-functional/testsuite/Magento/Quote/Api/GuestShipmentEstimationWithExtensionAttributesTest.php
@@ -0,0 +1,121 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Quote\Api;
+
+use Magento\Framework\Api\ExtensibleDataInterface;
+use Magento\TestFramework\ObjectManager;
+use Magento\TestFramework\TestCase\WebapiAbstract;
+use Magento\Quote\Api\Data\AddressInterface;
+
+class GuestShipmentEstimationWithExtensionAttributesTest extends WebapiAbstract
+{
+    const SERVICE_VERSION = 'V1';
+    const SERVICE_NAME = 'quoteGuestShipmentEstimationV1';
+    const RESOURCE_PATH = '/V1/guest-carts/';
+
+    /**
+     * @var ObjectManager
+     */
+    private $objectManager;
+
+    protected function setUp(): void
+    {
+        $this->objectManager = \Magento\TestFramework\Helper\Bootstrap::getObjectManager();
+    }
+
+    /**
+     * @magentoAppIsolation enabled
+     * @magentoDbIsolation disabled
+     * @magentoApiDataFixture Magento/SalesRule/_files/cart_rule_free_shipping.php
+     * @magentoApiDataFixture Magento/Sales/_files/quote.php
+     */
+    public function testEstimateByExtendedAddress(): void
+    {
+        /** @var \Magento\Quote\Model\Quote $quote */
+        $quote = $this->objectManager->create(\Magento\Quote\Model\Quote::class);
+        $quote->load('test01', 'reserved_order_id');
+        $cartId = $quote->getId();
+        if (!$cartId) {
+            $this->fail('quote fixture failed');
+        }
+
+        /** @var \Magento\Quote\Model\QuoteIdMask $quoteIdMask */
+        $quoteIdMask = \Magento\TestFramework\Helper\Bootstrap::getObjectManager()
+            ->create(\Magento\Quote\Model\QuoteIdMaskFactory::class)
+            ->create();
+        $quoteIdMask->load($cartId, 'quote_id');
+        //Use masked cart Id
+        $cartId = $quoteIdMask->getMaskedId();
+        $serviceInfo = [
+            'rest' => [
+                'resourcePath' => '/V1/guest-carts/' . $cartId . '/estimate-shipping-methods',
+                'httpMethod' => \Magento\Framework\Webapi\Rest\Request::HTTP_METHOD_POST,
+            ],
+            'soap' => [
+                'service' => self::SERVICE_NAME,
+                'serviceVersion' => 'V1',
+                'operation' => self::SERVICE_NAME . 'EstimateByExtendedAddress',
+            ],
+        ];
+        if (TESTS_WEB_API_ADAPTER == self::ADAPTER_SOAP) {
+            /** @var \Magento\Quote\Model\Quote\Address $address */
+            $address = $quote->getShippingAddress();
+
+            $data = [
+                AddressInterface::KEY_ID => (int)$address->getId(),
+                AddressInterface::KEY_REGION => $address->getRegion(),
+                AddressInterface::KEY_REGION_ID => $address->getRegionId(),
+                AddressInterface::KEY_REGION_CODE => $address->getRegionCode(),
+                AddressInterface::KEY_COUNTRY_ID => $address->getCountryId(),
+                AddressInterface::KEY_STREET => $address->getStreet(),
+                AddressInterface::KEY_COMPANY => $address->getCompany(),
+                AddressInterface::KEY_TELEPHONE => $address->getTelephone(),
+                AddressInterface::KEY_POSTCODE => $address->getPostcode(),
+                AddressInterface::KEY_CITY => $address->getCity(),
+                AddressInterface::KEY_FIRSTNAME => $address->getFirstname(),
+                AddressInterface::KEY_LASTNAME => $address->getLastname(),
+                AddressInterface::KEY_CUSTOMER_ID => $address->getCustomerId(),
+                AddressInterface::KEY_EMAIL => $address->getEmail(),
+                AddressInterface::SAME_AS_BILLING => $address->getSameAsBilling(),
+                AddressInterface::CUSTOMER_ADDRESS_ID => $address->getCustomerAddressId(),
+                AddressInterface::SAVE_IN_ADDRESS_BOOK => $address->getSaveInAddressBook(),
+                ExtensibleDataInterface::EXTENSION_ATTRIBUTES_KEY => [
+                    'discounts' => []
+                ]
+            ];
+
+            $requestData = [
+                'cartId' => $cartId,
+                'address' => $data
+            ];
+        } else {
+
+            $requestData = [
+                'address' => [
+                    'country_id' => "US",
+                    'postcode' => null,
+                    'region' => null,
+                    'region_id' => null,
+                    'extension_attributes' => [
+                        'discounts' => []
+                    ]
+                ]
+            ];
+        }
+
+        // Cart must be anonymous (see fixture)
+        $this->assertEmpty($quote->getCustomerId());
+
+        $result = $this->_webApiCall($serviceInfo, $requestData);
+
+        $this->assertNotEmpty($result);
+        $this->assertEquals(1, count($result));
+        foreach ($result as $rate) {
+            $this->assertEquals("flatrate", $rate['carrier_code']);
+            $this->assertEquals(0, $rate['amount']);
+        }
+    }
+}