diff --git a/php/class-coauthors-endpoint.php b/php/class-coauthors-endpoint.php
index cfeb2c15..d7424265 100644
--- a/php/class-coauthors-endpoint.php
+++ b/php/class-coauthors-endpoint.php
@@ -216,6 +216,7 @@ public function _format_author_data( $author ): array {
 			'email'        => sanitize_email( $author->user_email ),
 			'displayName'  => esc_html( str_replace( '∣', '|', $author->display_name ) ),
 			'avatar'       => esc_url( get_avatar_url( $author->ID ) ),
+			'userType'     => esc_html( $author->type ),
 		);
 	}
 
diff --git a/src/utils.js b/src/utils.js
index 4a3f9ec8..cb5e8146 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -66,16 +66,20 @@ export const addItemByValue = (
  * Format the author option object.
  *
  * @param {Object} root0              An author object from the API endpoint.
- * @param {Object} root0.displayName  Name to display in the UI.
- * @param {Object} root0.userNicename The unique username.
- * @param {Object} root0.email
+ * @param {string} root0.id           The author ID.
+ * @param {string} root0.displayName  Name to display in the UI.
+ * @param {string} root0.userNicename The unique username.
+ * @param {string} root0.email        The author's email address.
+ * @param {string} root0.userType     The entity type, either 'wpuser' or 'guest-user'.
  *
  * @return {Object} The object containing data relevant to the Coauthors component.
  */
-export const formatAuthorData = ( { displayName, userNicename, email } ) => {
+export const formatAuthorData = ( { id, displayName, userNicename, email, userType } ) => {
 	return {
+		id,
 		label: `${ displayName } | ${ email }`,
 		display: displayName,
 		value: userNicename,
+		userType,
 	};
 };