diff --git a/lib/Checkout/Payments/Setups/Common/Customer/Customer.php b/lib/Checkout/Payments/Setups/Common/Customer/Customer.php
index 3a36a590..d18f04c5 100644
--- a/lib/Checkout/Payments/Setups/Common/Customer/Customer.php
+++ b/lib/Checkout/Payments/Setups/Common/Customer/Customer.php
@@ -4,30 +4,66 @@
 
 use Checkout\Common\Phone;
 
+/**
+ * The customer's details.
+ */
 class Customer
 {
     /**
+     * Details of the customer's email.
+     * [Optional]
      * @var Email
      */
     public $email;
 
     /**
+     * The customer's full name.
+     * [Optional]
+     * max 100 characters
      * @var string
      */
     public $name;
 
     /**
+     * The customer's phone number.
+     * [Optional]
      * @var Phone
      */
     public $phone;
 
     /**
+     * Details of the customer's device.
+     * [Optional]
      * @var Device
      */
     public $device;
 
     /**
+     * Details of the account the customer holds with the merchant.
+     * [Optional]
      * @var MerchantAccount
      */
     public $merchant_account;
+
+    /**
+     * The unique identifier of the customer.
+     * [Optional]
+     * @var string
+     */
+    public $id;
+
+    /**
+     * The two-letter ISO country code of the customer for this payment.
+     * [Optional]
+     * min 2 characters, max 2 characters
+     * @var string value of Country
+     */
+    public $country;
+
+    /**
+     * The customer's tax identification number.
+     * [Optional]
+     * @var string
+     */
+    public $tax_number;
 }
diff --git a/lib/Checkout/Payments/Setups/Common/Customer/Device.php b/lib/Checkout/Payments/Setups/Common/Customer/Device.php
index 5bbe5fb1..24a1cc3b 100644
--- a/lib/Checkout/Payments/Setups/Common/Customer/Device.php
+++ b/lib/Checkout/Payments/Setups/Common/Customer/Device.php
@@ -2,10 +2,52 @@
 
 namespace Checkout\Payments\Setups\Common\Customer;
 
+/**
+ * Details of the customer's device.
+ */
 class Device
 {
     /**
+     * The locale of the device.
+     * [Optional]
      * @var string
      */
     public $locale;
+
+    /**
+     * A unique identifier for the customer's device.
+     * [Optional]
+     * @var string
+     */
+    public $fingerprint;
+
+    /**
+     * The customer's device IPv4 address, used by some payment methods for risk and eligibility checks.
+     * [Optional]
+     * @var string
+     */
+    public $ipv4;
+
+    /**
+     * The customer's device IPv6 address, used by some payment methods for risk and eligibility checks.
+     * [Optional]
+     * @var string
+     */
+    public $ipv6;
+
+    /**
+     * The type of client the customer uses to initiate the payment. Required when using Cash App Pay.
+     * [Optional]
+     * Enum: "web" "mobile_web" "app"
+     * @var string value of DeviceClient
+     */
+    public $client;
+
+    /**
+     * The operating system of the customer's device.
+     * [Optional]
+     * Enum: "android" "ios"
+     * @var string value of DeviceOs
+     */
+    public $os;
 }
diff --git a/lib/Checkout/Payments/Setups/Common/Customer/DeviceClient.php b/lib/Checkout/Payments/Setups/Common/Customer/DeviceClient.php
new file mode 100644
index 00000000..6ad9d20f
--- /dev/null
+++ b/lib/Checkout/Payments/Setups/Common/Customer/DeviceClient.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace Checkout\Payments\Setups\Common\Customer;
+
+/**
+ * The type of client the customer uses to initiate the payment.
+ */
+class DeviceClient
+{
+    /**
+     * A web browser on a desktop device.
+     * @var string
+     */
+    public static $web = "web";
+
+    /**
+     * A web browser on a mobile device.
+     * @var string
+     */
+    public static $mobile_web = "mobile_web";
+
+    /**
+     * A native mobile application.
+     * @var string
+     */
+    public static $app = "app";
+}
diff --git a/lib/Checkout/Payments/Setups/Common/Customer/DeviceOs.php b/lib/Checkout/Payments/Setups/Common/Customer/DeviceOs.php
new file mode 100644
index 00000000..fedacad5
--- /dev/null
+++ b/lib/Checkout/Payments/Setups/Common/Customer/DeviceOs.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Checkout\Payments\Setups\Common\Customer;
+
+/**
+ * The operating system of the customer's device.
+ */
+class DeviceOs
+{
+    /**
+     * Android.
+     * @var string
+     */
+    public static $android = "android";
+
+    /**
+     * iOS.
+     * @var string
+     */
+    public static $ios = "ios";
+}
diff --git a/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashApp.php b/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashApp.php
new file mode 100644
index 00000000..718d8fcc
--- /dev/null
+++ b/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashApp.php
@@ -0,0 +1,51 @@
+<?php
+
+namespace Checkout\Payments\Setups\Common\PaymentMethods\CashApp;
+
+use Checkout\Payments\Setups\Common\PaymentMethods\Common\PaymentMethodBase;
+
+/**
+ * The Cash App payment method's details and configuration.
+ *
+ * Inherits status, flags and initialization from PaymentMethodBase. Send initialization and
+ * customer_profile_sharing; the remaining properties are returned by the API only. To authorize the
+ * payment, send the customer to the redirect URL returned in the action. The customer device client
+ * (customer.device.client) is required when using this payment method.
+ */
+class CashApp extends PaymentMethodBase
+{
+    /**
+     * Indicates whether the customer consents to share their Cash App customer profile with Checkout.com.
+     * [Optional]
+     * @var bool
+     */
+    public $customer_profile_sharing;
+
+    /**
+     * The customer's Cash App profile that they consented to share. Included in the response when
+     * customer_profile_sharing is enabled.
+     * Cash App releases this profile only once. It's present in the first successful response when you get
+     * the Payment Setup after the customer authorizes the payment. Every subsequent response omits it.
+     * [Optional]
+     * readOnly
+     * @var CashAppCustomerProfile
+     */
+    public $customer_profile;
+
+    /**
+     * A reference for the Cash App Pay transaction, returned by the provider.
+     * [Optional]
+     * readOnly
+     * max 80 characters
+     * @var string
+     */
+    public $reference;
+
+    /**
+     * The next available action for the payment method.
+     * [Optional]
+     * readOnly
+     * @var CashAppAction
+     */
+    public $action;
+}
diff --git a/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppAction.php b/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppAction.php
new file mode 100644
index 00000000..b65de5fd
--- /dev/null
+++ b/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppAction.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace Checkout\Payments\Setups\Common\PaymentMethods\CashApp;
+
+/**
+ * The next available action for the Cash App payment method (response only).
+ */
+class CashAppAction
+{
+    /**
+     * The type of action.
+     * [Optional]
+     * readOnly
+     * Enum: "redirect"
+     * @var string value of CashAppActionType
+     */
+    public $type;
+
+    /**
+     * The URL to redirect the customer to so they can authorize the payment with Cash App.
+     * [Optional]
+     * readOnly
+     * Format: uri
+     * @var string
+     */
+    public $redirect_url;
+}
diff --git a/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppActionType.php b/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppActionType.php
new file mode 100644
index 00000000..08235357
--- /dev/null
+++ b/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppActionType.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace Checkout\Payments\Setups\Common\PaymentMethods\CashApp;
+
+/**
+ * The type of the Cash App payment method action.
+ */
+class CashAppActionType
+{
+    /**
+     * Redirect the customer to Cash App to authorize the payment.
+     * @var string
+     */
+    public static $redirect = "redirect";
+}
diff --git a/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppAddress.php b/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppAddress.php
new file mode 100644
index 00000000..f69a4604
--- /dev/null
+++ b/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppAddress.php
@@ -0,0 +1,77 @@
+<?php
+
+namespace Checkout\Payments\Setups\Common\PaymentMethods\CashApp;
+
+/**
+ * The address in a Cash App customer profile (response only).
+ *
+ * Uses Cash App's own key names (address_line_1, administrative_district_level_1), which differ from the
+ * Checkout.com Address (address_line1, city, state, zip). Do not replace it with the common Address.
+ */
+class CashAppAddress
+{
+    /**
+     * The first line of the address.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $address_line_1;
+
+    /**
+     * The second line of the address.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $address_line_2;
+
+    /**
+     * The third line of the address.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $address_line_3;
+
+    /**
+     * The address locality, such as the city or town.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $locality;
+
+    /**
+     * The address sublocality, such as the district or neighborhood.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $sublocality;
+
+    /**
+     * The address's top-level administrative district, such as the state or province.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $administrative_district_level_1;
+
+    /**
+     * The postal or zip code.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $postal_code;
+
+    /**
+     * The address country, in ISO 3166-1 alpha-2 format.
+     * [Optional]
+     * readOnly
+     * max 2 characters
+     * @var string value of Country
+     */
+    public $country;
+}
diff --git a/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppCustomerProfile.php b/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppCustomerProfile.php
new file mode 100644
index 00000000..f69aba85
--- /dev/null
+++ b/lib/Checkout/Payments/Setups/Common/PaymentMethods/CashApp/CashAppCustomerProfile.php
@@ -0,0 +1,118 @@
+<?php
+
+namespace Checkout\Payments\Setups\Common\PaymentMethods\CashApp;
+
+/**
+ * The customer's Cash App profile that they consented to share (response only).
+ */
+class CashAppCustomerProfile
+{
+    /**
+     * Cash App's identifier for the customer. This is not a Checkout.com customer identifier.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $customer_id;
+
+    /**
+     * The customer's $Cashtag.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $cashtag;
+
+    /**
+     * Cash App's reference for the customer profile.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $reference_id;
+
+    /**
+     * The customer's full name.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $full_name;
+
+    /**
+     * The customer's given name.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $given_name;
+
+    /**
+     * The customer's middle name.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $middle_name;
+
+    /**
+     * The customer's family name.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $family_name;
+
+    /**
+     * The suffix of the customer's name.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $suffix;
+
+    /**
+     * The customer's date of birth. Kept as a string because the provider's format varies (the API
+     * example is a date-time, for example 1990-01-01T00:00:00.0000000).
+     * [Optional]
+     * readOnly
+     * Format: date
+     * @var string
+     */
+    public $birth_date;
+
+    /**
+     * The customer's address.
+     * [Optional]
+     * readOnly
+     * @var CashAppAddress
+     */
+    public $address;
+
+    /**
+     * The customer's phone number.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $phone_number;
+
+    /**
+     * The customer's email address.
+     * [Optional]
+     * readOnly
+     * @var string
+     */
+    public $email_address;
+
+    /**
+     * The date and time the customer's Cash App account was created. Kept as a string because the
+     * provider's format varies (for example 1970-01-18T12:46:04.8000000+00:00, with seven
+     * fractional digits).
+     * [Optional]
+     * readOnly
+     * Format: date-time
+     * @var string
+     */
+    public $customer_since;
+}
diff --git a/lib/Checkout/Payments/Setups/Common/PaymentMethods/Common/PaymentMethodBase.php b/lib/Checkout/Payments/Setups/Common/PaymentMethods/Common/PaymentMethodBase.php
index a38621ba..3d13a8b5 100644
--- a/lib/Checkout/Payments/Setups/Common/PaymentMethods/Common/PaymentMethodBase.php
+++ b/lib/Checkout/Payments/Setups/Common/PaymentMethods/Common/PaymentMethodBase.php
@@ -5,17 +5,29 @@
 abstract class PaymentMethodBase
 {
     /**
-     * @var string
+     * The payment method status.
+     * [Optional]
+     * readOnly
+     * Enum: "unavailable" "action_required" "ready" "initialization_required" "invalid"
+     * @var string value of PaymentMethodStatus
      */
     public $status;
 
     /**
+     * The list of error codes or indicators that highlight missing or invalid information.
+     * [Optional]
+     * readOnly
      * @var string[]
      */
     public $flags;
 
     /**
-     * @var string
+     * The initialization state of the payment method. When you create a Payment Setup, this defaults to
+     * disabled.
+     * [Optional]
+     * Default: "disabled"
+     * Enum: "disabled" "enabled"
+     * @var string value of PaymentMethodInitialization
      */
     public $initialization;
 }
diff --git a/lib/Checkout/Payments/Setups/Common/PaymentMethods/Common/PaymentMethodInitialization.php b/lib/Checkout/Payments/Setups/Common/PaymentMethods/Common/PaymentMethodInitialization.php
new file mode 100644
index 00000000..f87e0aed
--- /dev/null
+++ b/lib/Checkout/Payments/Setups/Common/PaymentMethods/Common/PaymentMethodInitialization.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace Checkout\Payments\Setups\Common\PaymentMethods\Common;
+
+/**
+ * The initialization state of the payment method.
+ */
+class PaymentMethodInitialization
+{
+    /** @var string */
+    public static $disabled = "disabled";
+
+    /** @var string */
+    public static $enabled = "enabled";
+}
diff --git a/lib/Checkout/Payments/Setups/Common/PaymentMethods/Common/PaymentMethodStatus.php b/lib/Checkout/Payments/Setups/Common/PaymentMethods/Common/PaymentMethodStatus.php
new file mode 100644
index 00000000..0e5c3df2
--- /dev/null
+++ b/lib/Checkout/Payments/Setups/Common/PaymentMethods/Common/PaymentMethodStatus.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Checkout\Payments\Setups\Common\PaymentMethods\Common;
+
+/**
+ * The payment method status.
+ */
+class PaymentMethodStatus
+{
+    /** @var string */
+    public static $unavailable = "unavailable";
+
+    /** @var string */
+    public static $action_required = "action_required";
+
+    /** @var string */
+    public static $ready = "ready";
+
+    /** @var string */
+    public static $initialization_required = "initialization_required";
+
+    /** @var string */
+    public static $invalid = "invalid";
+}
diff --git a/lib/Checkout/Payments/Setups/Common/PaymentMethods/PaymentMethods.php b/lib/Checkout/Payments/Setups/Common/PaymentMethods/PaymentMethods.php
index 5045ce4c..019878cf 100644
--- a/lib/Checkout/Payments/Setups/Common/PaymentMethods/PaymentMethods.php
+++ b/lib/Checkout/Payments/Setups/Common/PaymentMethods/PaymentMethods.php
@@ -10,6 +10,7 @@
 use Checkout\Payments\Setups\Common\PaymentMethods\CardPresent\CardPresent;
 use Checkout\Payments\Setups\Common\PaymentMethods\PayByBank\PayByBank;
 use Checkout\Payments\Setups\Common\PaymentMethods\Stablecoin\Stablecoin;
+use Checkout\Payments\Setups\Common\PaymentMethods\CashApp\CashApp;
 
 class PaymentMethods
 {
@@ -68,4 +69,11 @@ class PaymentMethods
      * @var Stablecoin
      */
     public $stablecoin;
+
+    /**
+     * The Cash App payment method's details and configuration. Serialized under the key "cashapp".
+     * [Optional]
+     * @var CashApp
+     */
+    public $cashapp;
 }
diff --git a/test/Checkout/Tests/Payments/Setups/PaymentSetupFieldsSerializationTest.php b/test/Checkout/Tests/Payments/Setups/PaymentSetupFieldsSerializationTest.php
index 9ad33538..a0afb618 100644
--- a/test/Checkout/Tests/Payments/Setups/PaymentSetupFieldsSerializationTest.php
+++ b/test/Checkout/Tests/Payments/Setups/PaymentSetupFieldsSerializationTest.php
@@ -17,20 +17,40 @@
 use Checkout\Payments\AccommodationGuest;
 use Checkout\Payments\Setups\Common\Industry\PaymentSetupAccommodationRoom;
 use Checkout\Payments\Ticket;
+use Checkout\Common\Phone;
+use Checkout\Payments\Setups\Common\Customer\Customer;
+use Checkout\Payments\Setups\Common\Customer\Device;
+use Checkout\Payments\Setups\Common\Customer\DeviceClient;
+use Checkout\Payments\Setups\Common\Customer\DeviceOs;
+use Checkout\Payments\Setups\Common\Customer\Email;
+use Checkout\Payments\Setups\Common\Customer\MerchantAccount;
 use Checkout\Payments\Setups\Common\PaymentMethods\Bacs\Bacs;
 use Checkout\Payments\Setups\Common\PaymentMethods\Bacs\BacsAccountHolder;
 use Checkout\Payments\Setups\Common\PaymentMethods\Bacs\BacsAccountHolderType;
 use Checkout\Payments\Setups\Common\PaymentMethods\CardPresent\CardPresent;
+use Checkout\Payments\Setups\Common\PaymentMethods\CashApp\CashApp;
+use Checkout\Payments\Setups\Common\PaymentMethods\Common\PaymentMethodInitialization;
+use Checkout\Payments\Setups\Common\PaymentMethods\Common\PaymentMethodStatus;
+use Checkout\Payments\Setups\Common\PaymentMethods\CashApp\CashAppAction;
+use Checkout\Payments\Setups\Common\PaymentMethods\CashApp\CashAppActionType;
+use Checkout\Payments\Setups\Common\PaymentMethods\CashApp\CashAppAddress;
+use Checkout\Payments\Setups\Common\PaymentMethods\CashApp\CashAppCustomerProfile;
 use Checkout\Payments\Setups\Common\PaymentMethods\PayByBank\PayByBank;
 use Checkout\Payments\Setups\Common\PaymentMethods\PaymentMethods;
 use Checkout\Payments\Setups\Common\PaymentMethods\Stablecoin\Stablecoin;
 use Checkout\Payments\Setups\Common\PresentmentDetails\PaymentSetupPresentmentDetails;
 use Checkout\Payments\Setups\Common\Terminal\PaymentSetupTerminal;
 use Checkout\Payments\Setups\Request\PaymentSetupRequest;
+use DateTime;
 use PHPUnit\Framework\TestCase;
 
 class PaymentSetupFieldsSerializationTest extends TestCase
 {
+    const CASHAPP_REDIRECT_URL = "https://sandbox.api.cash.app/customer-request/v1/requests/"
+        . "GRR_f5xg6wrxhtv3p4w24g0wrexa/interstitial?validity_token=bap03y";
+
+    const CASHAPP_CUSTOMER_ID = "CST_AYVkuLzfsRqEhf4OyQFxQNv22m7IjNFjO6f2J5CDE2nxAC4-21wJ2H8_2kvsdIsDZMN4";
+
     public function testSerializesBillingDescriptorPresentmentDetailsAndTerminal()
     {
         $request = new PaymentSetupRequest();
@@ -276,4 +296,442 @@ public function testUnsetFieldsAreOmittedFromSerialization()
         $this->assertArrayNotHasKey('presentment_details', $decoded);
         $this->assertArrayNotHasKey('terminal', $decoded);
     }
+
+    public function testSerializesCashAppUnderLiteralKeyWithMerchantFields()
+    {
+        $cashApp = new CashApp();
+        $cashApp->initialization = "enabled";
+        $cashApp->customer_profile_sharing = true;
+
+        $paymentMethods = new PaymentMethods();
+        $paymentMethods->cashapp = $cashApp;
+
+        $request = new PaymentSetupRequest();
+        $request->processing_channel_id = "pc_aaaaaaaaaaaaaaaaaaaaaaaaaa";
+        $request->amount = 1000;
+        $request->currency = "USD";
+        $request->payment_methods = $paymentMethods;
+
+        $json = (new JsonSerializer())->serialize($request);
+        $decoded = json_decode($json, true);
+
+        $this->assertStringContainsString('"cashapp":', $json);
+        $this->assertStringNotContainsString('cash_app', $json);
+        $this->assertStringNotContainsString('cashApp', $json);
+        $this->assertStringNotContainsString('customerProfileSharing', $json);
+        $this->assertSame(
+            ["initialization" => "enabled", "customer_profile_sharing" => true],
+            $decoded['payment_methods']['cashapp']
+        );
+    }
+
+    public function testSerializesCustomerProfileSharingFalse()
+    {
+        $cashApp = new CashApp();
+        $cashApp->initialization = "enabled";
+        $cashApp->customer_profile_sharing = false;
+
+        $decoded = json_decode((new JsonSerializer())->serialize($cashApp), true);
+
+        // The serializer strips nulls only; an explicit false must still reach the API.
+        $this->assertArrayHasKey("customer_profile_sharing", $decoded);
+        $this->assertFalse($decoded["customer_profile_sharing"]);
+    }
+
+    public function testSerializesEveryDeviceClientValue()
+    {
+        $serializer = new JsonSerializer();
+        $device = new Device();
+
+        $device->client = DeviceClient::$web;
+        $this->assertSame('{"client":"web"}', $serializer->serialize($device));
+
+        $device->client = DeviceClient::$mobile_web;
+        $this->assertSame('{"client":"mobile_web"}', $serializer->serialize($device));
+
+        $device->client = DeviceClient::$app;
+        $this->assertSame('{"client":"app"}', $serializer->serialize($device));
+    }
+
+    public function testSerializesEveryDeviceOsValue()
+    {
+        $serializer = new JsonSerializer();
+        $device = new Device();
+
+        $device->os = DeviceOs::$android;
+        $this->assertSame('{"os":"android"}', $serializer->serialize($device));
+
+        $device->os = DeviceOs::$ios;
+        $this->assertSame('{"os":"ios"}', $serializer->serialize($device));
+    }
+
+    public function testSerializesAllDeviceFields()
+    {
+        $device = new Device();
+        $device->locale = "en_US";
+        $device->fingerprint = "fp_abc123xyz";
+        $device->ipv4 = "203.0.113.0";
+        $device->ipv6 = "2001:db8:85a3::8a2e:370:7334";
+        $device->client = DeviceClient::$web;
+        $device->os = DeviceOs::$android;
+
+        $customer = new Customer();
+        $customer->device = $device;
+        $request = new PaymentSetupRequest();
+        $request->customer = $customer;
+
+        $decoded = json_decode((new JsonSerializer())->serialize($request), true);
+
+        $this->assertSame(
+            [
+                "locale" => "en_US",
+                "fingerprint" => "fp_abc123xyz",
+                "ipv4" => "203.0.113.0",
+                "ipv6" => "2001:db8:85a3::8a2e:370:7334",
+                "client" => "web",
+                "os" => "android",
+            ],
+            $decoded['customer']['device']
+        );
+    }
+
+    public function testSerializesDeviceWithOnlyLocale()
+    {
+        $device = new Device();
+        $device->locale = "en_US";
+
+        $this->assertSame('{"locale":"en_US"}', (new JsonSerializer())->serialize($device));
+    }
+
+    public function testCashAppRoundTripKeepsEveryProperty()
+    {
+        $address = new CashAppAddress();
+        $address->address_line_1 = "123 Main St";
+        $address->address_line_2 = "Apt 2";
+        $address->address_line_3 = "Floor 3";
+        $address->locality = "Springfield";
+        $address->sublocality = "Downtown";
+        $address->administrative_district_level_1 = "IL";
+        $address->postal_code = "62701";
+        $address->country = "US";
+
+        $profile = new CashAppCustomerProfile();
+        $profile->customer_id = self::CASHAPP_CUSTOMER_ID;
+        $profile->cashtag = '$CASHTAG_C_TOKEN';
+        $profile->reference_id = "value";
+        $profile->full_name = "John Middle Doe";
+        $profile->given_name = "John";
+        $profile->middle_name = "Middle";
+        $profile->family_name = "Doe";
+        $profile->suffix = "Jr.";
+        $profile->birth_date = "1990-01-01T00:00:00.0000000";
+        $profile->address = $address;
+        $profile->phone_number = "5555555555";
+        $profile->email_address = "cash@cash.com";
+        $profile->customer_since = "1970-01-18T12:46:04.8000000+00:00";
+
+        $action = new CashAppAction();
+        $action->type = CashAppActionType::$redirect;
+        $action->redirect_url = self::CASHAPP_REDIRECT_URL;
+
+        $cashApp = new CashApp();
+        $cashApp->status = "action_required";
+        $cashApp->flags = [];
+        $cashApp->initialization = "enabled";
+        $cashApp->customer_profile_sharing = true;
+        $cashApp->reference = "ORDER-99";
+        $cashApp->action = $action;
+        $cashApp->customer_profile = $profile;
+
+        $serializer = new JsonSerializer();
+        $json = $serializer->serialize($cashApp);
+        $decoded = $serializer->deserialize($json);
+
+        $this->assertStringContainsString('"address_line_1":', $json);
+        $this->assertStringContainsString('"address_line_2":', $json);
+        $this->assertStringContainsString('"address_line_3":', $json);
+        $this->assertStringContainsString('"administrative_district_level_1":', $json);
+        $this->assertStringNotContainsString('"address_line1"', $json);
+        $this->assertStringNotContainsString('"administrative_district_level1"', $json);
+
+        $this->assertSame("action_required", $decoded['status']);
+        $this->assertSame([], $decoded['flags']);
+        $this->assertSame("enabled", $decoded['initialization']);
+        $this->assertTrue($decoded['customer_profile_sharing']);
+        $this->assertSame("ORDER-99", $decoded['reference']);
+        $this->assertSame("redirect", $decoded['action']['type']);
+        $this->assertSame(self::CASHAPP_REDIRECT_URL, $decoded['action']['redirect_url']);
+
+        $decodedProfile = $decoded['customer_profile'];
+        $this->assertCount(13, $decodedProfile);
+        $this->assertSame(self::CASHAPP_CUSTOMER_ID, $decodedProfile['customer_id']);
+        $this->assertSame('$CASHTAG_C_TOKEN', $decodedProfile['cashtag']);
+        $this->assertSame("value", $decodedProfile['reference_id']);
+        $this->assertSame("John Middle Doe", $decodedProfile['full_name']);
+        $this->assertSame("John", $decodedProfile['given_name']);
+        $this->assertSame("Middle", $decodedProfile['middle_name']);
+        $this->assertSame("Doe", $decodedProfile['family_name']);
+        $this->assertSame("Jr.", $decodedProfile['suffix']);
+        $this->assertSame("1990-01-01T00:00:00.0000000", $decodedProfile['birth_date']);
+        $this->assertSame("5555555555", $decodedProfile['phone_number']);
+        $this->assertSame("cash@cash.com", $decodedProfile['email_address']);
+        $this->assertSame("1970-01-18T12:46:04.8000000+00:00", $decodedProfile['customer_since']);
+        $this->assertSame(
+            [
+                "address_line_1" => "123 Main St",
+                "address_line_2" => "Apt 2",
+                "address_line_3" => "Floor 3",
+                "locality" => "Springfield",
+                "sublocality" => "Downtown",
+                "administrative_district_level_1" => "IL",
+                "postal_code" => "62701",
+                "country" => "US",
+            ],
+            $decodedProfile['address']
+        );
+    }
+
+    public function testDeserializesCashAppSwaggerExampleResponse()
+    {
+        $json = '{
+            "id": "ps_2Un4Ld0Qm8Dj6kXHm0LqT0bK5mL",
+            "payment_methods": {
+                "cashapp": {
+                    "status": "action_required",
+                    "flags": [],
+                    "initialization": "enabled",
+                    "customer_profile_sharing": true,
+                    "reference": "ORDER-99",
+                    "action": {
+                        "type": "redirect",
+                        "redirect_url": "' . self::CASHAPP_REDIRECT_URL . '"
+                    },
+                    "customer_profile": {
+                        "customer_id": "' . self::CASHAPP_CUSTOMER_ID . '",
+                        "cashtag": "$CASHTAG_C_TOKEN",
+                        "reference_id": "value",
+                        "full_name": "John Middle Doe",
+                        "given_name": "John",
+                        "middle_name": "Middle",
+                        "family_name": "Doe",
+                        "suffix": "Jr.",
+                        "birth_date": "1990-01-01T00:00:00.0000000",
+                        "address": {
+                            "address_line_1": "123 Main St",
+                            "address_line_2": "Apt 2",
+                            "address_line_3": "Floor 3",
+                            "locality": "Springfield",
+                            "sublocality": "Downtown",
+                            "administrative_district_level_1": "IL",
+                            "postal_code": "62701",
+                            "country": "US"
+                        },
+                        "phone_number": "5555555555",
+                        "email_address": "cash@cash.com",
+                        "customer_since": "1970-01-18T12:46:04.8000000+00:00"
+                    }
+                }
+            },
+            "customer": {
+                "device": {
+                    "locale": "en_US",
+                    "fingerprint": "fp_abc123xyz",
+                    "ipv4": "203.0.113.0",
+                    "ipv6": "2001:db8:85a3::8a2e:370:7334",
+                    "client": "web",
+                    "os": "android"
+                }
+            }
+        }';
+
+        $response = (new JsonSerializer())->deserialize($json);
+        $cashApp = $response['payment_methods']['cashapp'];
+
+        $this->assertSame("action_required", $cashApp['status']);
+        $this->assertSame([], $cashApp['flags']);
+        $this->assertSame("enabled", $cashApp['initialization']);
+        $this->assertTrue($cashApp['customer_profile_sharing']);
+        $this->assertSame("ORDER-99", $cashApp['reference']);
+        $this->assertSame(CashAppActionType::$redirect, $cashApp['action']['type']);
+        $this->assertSame(self::CASHAPP_REDIRECT_URL, $cashApp['action']['redirect_url']);
+
+        $profile = $cashApp['customer_profile'];
+        $this->assertCount(13, $profile);
+        $this->assertSame(self::CASHAPP_CUSTOMER_ID, $profile['customer_id']);
+        $this->assertSame('$CASHTAG_C_TOKEN', $profile['cashtag']);
+        $this->assertSame("value", $profile['reference_id']);
+        $this->assertSame("John Middle Doe", $profile['full_name']);
+        $this->assertSame("John", $profile['given_name']);
+        $this->assertSame("Middle", $profile['middle_name']);
+        $this->assertSame("Doe", $profile['family_name']);
+        $this->assertSame("Jr.", $profile['suffix']);
+        $this->assertSame("1990-01-01T00:00:00.0000000", $profile['birth_date']);
+        $this->assertSame("5555555555", $profile['phone_number']);
+        $this->assertSame("cash@cash.com", $profile['email_address']);
+        $this->assertSame("1970-01-18T12:46:04.8000000+00:00", $profile['customer_since']);
+
+        $address = $profile['address'];
+        $this->assertCount(8, $address);
+        $this->assertSame("123 Main St", $address['address_line_1']);
+        $this->assertSame("Apt 2", $address['address_line_2']);
+        $this->assertSame("Floor 3", $address['address_line_3']);
+        $this->assertSame("Springfield", $address['locality']);
+        $this->assertSame("Downtown", $address['sublocality']);
+        $this->assertSame("IL", $address['administrative_district_level_1']);
+        $this->assertSame("62701", $address['postal_code']);
+        $this->assertSame("US", $address['country']);
+
+        $device = $response['customer']['device'];
+        $this->assertSame("en_US", $device['locale']);
+        $this->assertSame("fp_abc123xyz", $device['fingerprint']);
+        $this->assertSame("203.0.113.0", $device['ipv4']);
+        $this->assertSame("2001:db8:85a3::8a2e:370:7334", $device['ipv6']);
+        $this->assertSame(DeviceClient::$web, $device['client']);
+        $this->assertSame(DeviceOs::$android, $device['os']);
+    }
+
+    public function testCustomerRoundTripKeepsAllEightProperties()
+    {
+        $email = new Email();
+        $email->address = "johnsmith@example.com";
+        $email->verified = true;
+
+        $phone = new Phone();
+        $phone->country_code = "+44";
+        $phone->number = "207 946 0000";
+
+        $device = new Device();
+        $device->locale = "en_GB";
+        $device->fingerprint = "fp_abc123xyz";
+        $device->ipv4 = "203.0.113.0";
+        $device->ipv6 = "2001:db8:85a3::8a2e:370:7334";
+        $device->client = DeviceClient::$app;
+        $device->os = DeviceOs::$ios;
+
+        $merchantAccount = new MerchantAccount();
+        $merchantAccount->id = "1234";
+        $merchantAccount->registration_date = new DateTime("2023-05-01");
+        $merchantAccount->last_modified = new DateTime("2023-05-01");
+        $merchantAccount->returning_customer = true;
+        $merchantAccount->first_transaction_date = new DateTime("2023-09-15");
+        $merchantAccount->last_transaction_date = new DateTime("2025-03-28");
+        $merchantAccount->total_order_count = 6;
+        $merchantAccount->last_payment_amount = 55;
+
+        $customer = new Customer();
+        $customer->email = $email;
+        $customer->name = "John Smith";
+        $customer->phone = $phone;
+        $customer->device = $device;
+        $customer->merchant_account = $merchantAccount;
+        $customer->id = "cus_123456789";
+        $customer->country = "GB";
+        $customer->tax_number = "GB123456789";
+
+        $serializer = new JsonSerializer();
+        $json = $serializer->serialize($customer);
+        $decoded = $serializer->deserialize($json);
+
+        $this->assertStringContainsString('"tax_number":"GB123456789"', $json);
+        $this->assertStringNotContainsString('taxNumber', $json);
+        $this->assertCount(8, $decoded);
+        $this->assertSame("cus_123456789", $decoded['id']);
+        $this->assertSame("GB", $decoded['country']);
+        $this->assertSame("GB123456789", $decoded['tax_number']);
+        $this->assertSame("John Smith", $decoded['name']);
+        $this->assertSame(["address" => "johnsmith@example.com", "verified" => true], $decoded['email']);
+        $this->assertSame(["country_code" => "+44", "number" => "207 946 0000"], $decoded['phone']);
+        $this->assertSame(
+            [
+                "locale" => "en_GB",
+                "fingerprint" => "fp_abc123xyz",
+                "ipv4" => "203.0.113.0",
+                "ipv6" => "2001:db8:85a3::8a2e:370:7334",
+                "client" => "app",
+                "os" => "ios",
+            ],
+            $decoded['device']
+        );
+        $this->assertSame(
+            [
+                "id" => "1234",
+                "registration_date" => "2023-05-01",
+                "last_modified" => "2023-05-01",
+                "returning_customer" => true,
+                "first_transaction_date" => "2023-09-15",
+                "last_transaction_date" => "2025-03-28",
+                "total_order_count" => 6,
+                "last_payment_amount" => 55,
+            ],
+            $decoded['merchant_account']
+        );
+    }
+
+    public function testDeserializesCustomerSwaggerExample()
+    {
+        $json = '{
+            "customer": {
+                "country": "GB",
+                "id": "cus_123456789",
+                "email": { "address": "johnsmith@example.com", "verified": true },
+                "name": "John Smith",
+                "tax_number": "GB123456789",
+                "phone": { "country_code": "+44", "number": "207 946 0000" },
+                "device": {
+                    "locale": "en_GB",
+                    "fingerprint": "fp_abc123xyz",
+                    "ipv4": "203.0.113.0",
+                    "ipv6": "2001:db8:85a3::8a2e:370:7334",
+                    "client": "web",
+                    "os": "android"
+                },
+                "merchant_account": {
+                    "id": "1234",
+                    "registration_date": "2023-05-01T00:00:00.0000000",
+                    "last_modified": "2023-05-01T00:00:00.0000000",
+                    "returning_customer": true,
+                    "first_transaction_date": "2023-09-15T00:00:00.0000000",
+                    "last_transaction_date": "2025-03-28T00:00:00.0000000",
+                    "total_order_count": 6,
+                    "last_payment_amount": 55.99
+                }
+            }
+        }';
+
+        $customer = (new JsonSerializer())->deserialize($json)['customer'];
+
+        $this->assertSame("GB", $customer['country']);
+        $this->assertSame("cus_123456789", $customer['id']);
+        $this->assertSame("johnsmith@example.com", $customer['email']['address']);
+        $this->assertTrue($customer['email']['verified']);
+        $this->assertSame("John Smith", $customer['name']);
+        $this->assertSame("GB123456789", $customer['tax_number']);
+        $this->assertSame("+44", $customer['phone']['country_code']);
+        $this->assertSame("207 946 0000", $customer['phone']['number']);
+        $this->assertSame("en_GB", $customer['device']['locale']);
+        $this->assertSame("fp_abc123xyz", $customer['device']['fingerprint']);
+        $this->assertSame("203.0.113.0", $customer['device']['ipv4']);
+        $this->assertSame("2001:db8:85a3::8a2e:370:7334", $customer['device']['ipv6']);
+        $this->assertSame(DeviceClient::$web, $customer['device']['client']);
+        $this->assertSame(DeviceOs::$android, $customer['device']['os']);
+        $this->assertSame("1234", $customer['merchant_account']['id']);
+        $this->assertSame("2023-05-01T00:00:00.0000000", $customer['merchant_account']['registration_date']);
+        $this->assertSame("2023-05-01T00:00:00.0000000", $customer['merchant_account']['last_modified']);
+        $this->assertTrue($customer['merchant_account']['returning_customer']);
+        $this->assertSame("2023-09-15T00:00:00.0000000", $customer['merchant_account']['first_transaction_date']);
+        $this->assertSame("2025-03-28T00:00:00.0000000", $customer['merchant_account']['last_transaction_date']);
+        $this->assertSame(6, $customer['merchant_account']['total_order_count']);
+        $this->assertSame(55.99, $customer['merchant_account']['last_payment_amount']);
+    }
+
+    public function testPaymentMethodStatusAndInitializationConstantsMatchTheSpec()
+    {
+        $this->assertSame("unavailable", PaymentMethodStatus::$unavailable);
+        $this->assertSame("action_required", PaymentMethodStatus::$action_required);
+        $this->assertSame("ready", PaymentMethodStatus::$ready);
+        $this->assertSame("initialization_required", PaymentMethodStatus::$initialization_required);
+        $this->assertSame("invalid", PaymentMethodStatus::$invalid);
+        $this->assertSame("disabled", PaymentMethodInitialization::$disabled);
+        $this->assertSame("enabled", PaymentMethodInitialization::$enabled);
+    }
 }
diff --git a/test/Checkout/Tests/Payments/Setups/PaymentSetupsClientTest.php b/test/Checkout/Tests/Payments/Setups/PaymentSetupsClientTest.php
index b6309278..0eafd9f1 100644
--- a/test/Checkout/Tests/Payments/Setups/PaymentSetupsClientTest.php
+++ b/test/Checkout/Tests/Payments/Setups/PaymentSetupsClientTest.php
@@ -115,6 +115,28 @@ public function shouldConfirmPaymentSetup()
         $this->assertNotNull($response);
     }
 
+    /**
+     * @test
+     * @throws CheckoutApiException
+     */
+    public function shouldConfirmPaymentSetupWithCashApp()
+    {
+        $paymentSetupId = "setup_123456";
+
+        $this->apiClient
+            ->expects($this->once())
+            ->method("post")
+            ->with(
+                $this->equalTo("payments/setups/" . $paymentSetupId . "/confirm/cashapp"),
+                $this->isNull(),
+                $this->anything()
+            )
+            ->willReturn(["response"]);
+
+        $response = $this->client->confirmPaymentSetup($paymentSetupId, "cashapp");
+        $this->assertNotNull($response);
+    }
+
     /**
      * @test
      * @throws CheckoutApiException
diff --git a/test/Checkout/Tests/Payments/Setups/PaymentSetupsIntegrationTest.php b/test/Checkout/Tests/Payments/Setups/PaymentSetupsIntegrationTest.php
index c61dde21..f6294b4f 100644
--- a/test/Checkout/Tests/Payments/Setups/PaymentSetupsIntegrationTest.php
+++ b/test/Checkout/Tests/Payments/Setups/PaymentSetupsIntegrationTest.php
@@ -16,6 +16,9 @@
 use Checkout\Payments\Setups\Common\Customer\Customer;
 use Checkout\Payments\Setups\Common\Customer\Email;
 use Checkout\Payments\Setups\Common\Customer\Device;
+use Checkout\Payments\Setups\Common\Customer\DeviceClient;
+use Checkout\Payments\Setups\Common\Customer\DeviceOs;
+use Checkout\Payments\Setups\Common\PaymentMethods\CashApp\CashApp;
 use Checkout\Payments\PaymentType;
 use Checkout\PlatformType;
 use Checkout\Tests\SandboxTestFixture;
@@ -137,6 +140,86 @@ public function shouldConfirmPaymentSetup()
         $this->assertNotNull($response["processed_on"]);
     }
 
+    /**
+     * @test
+     * @throws CheckoutApiException
+     */
+    public function shouldCreatePaymentSetupWithDeviceFieldsAndEchoThem()
+    {
+        // Arrange
+        $request = $this->createPaymentSetupRequest();
+        $request->customer->device->fingerprint = "fp_abc123xyz";
+        $request->customer->device->ipv4 = "203.0.113.0";
+        $request->customer->device->ipv6 = "2001:db8:85a3::8a2e:370:7334";
+        $request->customer->device->client = DeviceClient::$web;
+        $request->customer->device->os = DeviceOs::$android;
+
+        // Act
+        $response = $this->checkoutApi->getPaymentSetupsClient()->createPaymentSetup($request);
+
+        // Assert
+        $device = $response["customer"]["device"];
+        $this->assertEquals("en_GB", $device["locale"]);
+        $this->assertEquals("fp_abc123xyz", $device["fingerprint"]);
+        $this->assertEquals("203.0.113.0", $device["ipv4"]);
+        $this->assertEquals("2001:db8:85a3::8a2e:370:7334", $device["ipv6"]);
+        $this->assertEquals("web", $device["client"]);
+        $this->assertEquals("android", $device["os"]);
+    }
+
+    /**
+     * @test
+     * @throws CheckoutApiException
+     */
+    public function shouldCreatePaymentSetupWithCustomerIdentifiersAndEchoThem()
+    {
+        // Arrange
+        $request = $this->createPaymentSetupRequest();
+        $request->customer->id = "cus_123456789";
+        $request->customer->country = "GB";
+        $request->customer->tax_number = "GB123456789";
+
+        // Act
+        $response = $this->checkoutApi->getPaymentSetupsClient()->createPaymentSetup($request);
+
+        // Assert
+        $this->assertEquals("cus_123456789", $response["customer"]["id"]);
+        $this->assertEquals("GB", $response["customer"]["country"]);
+        $this->assertEquals("GB123456789", $response["customer"]["tax_number"]);
+    }
+
+    /**
+     * @test
+     * @throws CheckoutApiException
+     */
+    public function shouldCreatePaymentSetupWithCashAppAndReturnItsState()
+    {
+        // Arrange
+        $request = $this->createPaymentSetupRequest();
+        $request->currency = Currency::$USD;
+        $request->customer->device->client = DeviceClient::$web;
+        $cashApp = new CashApp();
+        $cashApp->initialization = "enabled";
+        $cashApp->customer_profile_sharing = true;
+        $request->payment_methods = new PaymentMethods();
+        $request->payment_methods->cashapp = $cashApp;
+
+        // Act
+        $response = $this->checkoutApi->getPaymentSetupsClient()->createPaymentSetup($request);
+
+        // Assert
+        $available = isset($response["available_payment_methods"]) ? $response["available_payment_methods"] : [];
+        if (!in_array("cashapp", $available, true)) {
+            $this->markTestSkipped("Cash App Pay is not enabled on the sandbox processing channel");
+        }
+        $fetched = $this->checkoutApi->getPaymentSetupsClient()->getPaymentSetup($response["id"]);
+        $this->assertArrayHasKey("cashapp", $fetched["payment_methods"]);
+        $cashAppResponse = $fetched["payment_methods"]["cashapp"];
+        $this->assertNotNull($cashAppResponse["status"]);
+        $this->assertEquals("enabled", $cashAppResponse["initialization"]);
+        $this->assertTrue($cashAppResponse["customer_profile_sharing"]);
+    }
+
     /**
      * @return PaymentSetupRequest
      */