diff --git a/modules/ppcp-settings/src/Endpoint/LoginLinkRestEndpoint.php b/modules/ppcp-settings/src/Endpoint/LoginLinkRestEndpoint.php
index b9972349f..3d6c45843 100644
--- a/modules/ppcp-settings/src/Endpoint/LoginLinkRestEndpoint.php
+++ b/modules/ppcp-settings/src/Endpoint/LoginLinkRestEndpoint.php
@@ -82,6 +82,16 @@ class LoginLinkRestEndpoint extends RestEndpoint {
 							return array_map( 'sanitize_text_field', $products );
 						},
 					),
+					'options'    => array(
+						'requires'          => false,
+						'type'              => 'array',
+						'items'             => array(
+							'type' => 'bool',
+						),
+						'sanitize_callback' => function ( $flags ) {
+							return array_map( array( $this, 'to_boolean' ), $flags );
+						},
+					),
 				),
 			)
 		);
@@ -97,9 +107,10 @@ class LoginLinkRestEndpoint extends RestEndpoint {
 	public function get_login_url( WP_REST_Request $request ) : WP_REST_Response {
 		$use_sandbox = $request->get_param( 'useSandbox' );
 		$products    = $request->get_param( 'products' );
+		$flags       = (array) $request->get_param( 'options' );
 
 		try {
-			$url = $this->url_generator->generate( $products, $use_sandbox );
+			$url = $this->url_generator->generate( $products, $flags, $use_sandbox );
 
 			return $this->return_success( $url );
 		} catch ( \Exception $e ) {
diff --git a/modules/ppcp-settings/src/Service/ConnectionUrlGenerator.php b/modules/ppcp-settings/src/Service/ConnectionUrlGenerator.php
index 1d9084912..c3204ccf1 100644
--- a/modules/ppcp-settings/src/Service/ConnectionUrlGenerator.php
+++ b/modules/ppcp-settings/src/Service/ConnectionUrlGenerator.php
@@ -82,12 +82,13 @@ class ConnectionUrlGenerator {
 	 *
 	 * @param array $products    An array of product identifiers to include in the sign-up process.
 	 *                           These determine the PayPal onboarding experience.
+	 * @param array $flags       Onboarding choices that will customize the ISU payload.
 	 * @param bool  $use_sandbox Whether to generate a sandbox URL.
 	 *
 	 * @return string The generated PayPal onboarding URL.
 	 */
-	public function generate( array $products = array(), bool $use_sandbox = false ) : string {
-		$cache_key      = $this->cache_key( $products, $use_sandbox );
+	public function generate( array $products = array(), array $flags = array(), bool $use_sandbox = false ) : string {
+		$cache_key      = $this->cache_key( $products, $flags, $use_sandbox );
 		$user_id        = get_current_user_id();
 		$onboarding_url = $this->url_manager->get( $cache_key, $user_id );
 		$cached_url     = $this->try_get_from_cache( $onboarding_url, $cache_key );
@@ -100,7 +101,7 @@ class ConnectionUrlGenerator {
 
 		$this->logger->info( 'Generating onboarding URL for: ' . $cache_key );
 
-		$url = $this->generate_new_url( $use_sandbox, $products, $onboarding_url, $cache_key );
+		$url = $this->generate_new_url( $use_sandbox, $products, $flags, $onboarding_url, $cache_key );
 
 		if ( $url ) {
 			$this->persist_url( $onboarding_url, $url );
@@ -112,18 +113,28 @@ class ConnectionUrlGenerator {
 	/**
 	 * Generates a cache key from the environment and sorted product array.
 	 *
+	 * Q: Why do we cache the connection URL?
+	 * A: The URL is generated by a partner-referrals API, i.e. it requires a
+	 *    remote request; caching the response avoids unnecessary API calls.
+	 *
 	 * @param array $products    Product identifiers that are part of the cache key.
+	 * @param array $flags       Onboarding flags.
 	 * @param bool  $for_sandbox Whether the cache contains a sandbox URL.
 	 *
 	 * @return string The cache key, defining the product list and environment.
 	 */
-	protected function cache_key( array $products, bool $for_sandbox ) : string {
+	protected function cache_key( array $products, array $flags, bool $for_sandbox ) : string {
 		$environment = $for_sandbox ? 'sandbox' : 'production';
 
 		// Sort products alphabetically, to improve cache implementation.
 		sort( $products );
 
-		return $environment . '-' . implode( '-', $products );
+		// Extract the names of active flags.
+		$active_flags = array_keys( array_filter( $flags ) );
+
+		return strtolower(
+			$environment . '-' . implode( '-', $products ) . '-' . implode( '-', $active_flags )
+		);
 	}
 
 	/**
@@ -162,12 +173,13 @@ class ConnectionUrlGenerator {
 	 *
 	 * @param bool          $for_sandbox    Whether to generate a sandbox URL.
 	 * @param array         $products       The products array.
+	 * @param array         $flags          Onboarding flags.
 	 * @param OnboardingUrl $onboarding_url The OnboardingUrl object.
 	 * @param string        $cache_key      The cache key.
 	 *
 	 * @return string The generated URL or an empty string on failure.
 	 */
-	protected function generate_new_url( bool $for_sandbox, array $products, OnboardingUrl $onboarding_url, string $cache_key ) : string {
+	protected function generate_new_url( bool $for_sandbox, array $products, array $flags, OnboardingUrl $onboarding_url, string $cache_key ) : string {
 		$query_args = array( 'displayMode' => 'minibrowser' );
 		$onboarding_url->init();
 
@@ -179,7 +191,7 @@ class ConnectionUrlGenerator {
 			return '';
 		}
 
-		$data = $this->prepare_referral_data( $products, $onboarding_token );
+		$data = $this->prepare_referral_data( $products, $flags, $onboarding_token );
 
 		try {
 			$referral = $this->partner_referrals->get_value( $for_sandbox );
@@ -197,12 +209,18 @@ class ConnectionUrlGenerator {
 	 * Prepares the referral data.
 	 *
 	 * @param array  $products         The products array.
+	 * @param array  $flags            Onboarding flags.
 	 * @param string $onboarding_token The onboarding token.
 	 *
 	 * @return array The prepared referral data.
 	 */
-	protected function prepare_referral_data( array $products, string $onboarding_token ) : array {
-		return $this->referrals_data->data( $products, $onboarding_token );
+	protected function prepare_referral_data( array $products, array $flags, string $onboarding_token ) : array {
+		return $this->referrals_data->data(
+			$products,
+			$onboarding_token,
+			(bool) ( $flags['useSubscriptions'] ?? false ),
+			(bool) ( $flags['useCardPayments'] ?? false )
+		);
 	}
 
 	/**