Add "IsAccessibleForFree" to the Article schema

Add to posts with the "premium" tag

<?php
/********* DO NOT COPY THE PARTS ABOVE THIS LINE *********/

/* 
 * Conditionally sets 'isAccessibleForFree' in Yoast's Article schema based on the 'premium' post tag.
 * - If a post has the 'premium' tag, isAccessibleForFree is set to 'false'.
 * - For all other posts, isAccessibleForFree is set to 'true'.
 *
 * Credit: Yoast team
 * Last Tested: Jun 24 2025 using Yoast SEO 25.3.1 on WordPress 6.8.1
 * Documentation: https://developer.yoast.com/features/schema/pieces/article/#api
 * 
 * NOTE: This function checks for a tag with the SLUG 'premium'. If your tag's slug is different
 * (e.g., 'premium-content'), you must update the 'premium' string in the has_tag() function below.
 * 
 * @param array $data The Article schema data.
 * @return array The modified schema data.
*/
function add_is_accessible_for_free_to_article_schema( $data ) {
	// Get the ID of the current post being processed by Yoast.
	$post_id = get_the_ID();

	// If we can't determine the post ID, return the original data without adding the property.
	if ( ! $post_id ) {
		return $data;
	}

	// Check if the current post has the tag with the slug 'premium'.
	if ( has_tag( 'premium', $post_id ) ) {
		// If the 'premium' tag exists, the content is behind a paywall (not free).
		$data['isAccessibleForFree'] = false;
	} else {
		// Otherwise, the content is accessible for free.
		$data['isAccessibleForFree'] = true;
	}

	return $data;
}

add_filter( 'wpseo_schema_article', 'add_is_accessible_for_free_to_article_schema' );

IsAccessibleForFree.php

/**
 * Add the 'isAccessibleForFree' property to Yoast's Article schema.
 *
 * @param array $data The Article schema data.
 * @return array The modified schema data.
 */

function add_is_accessible_for_free_to_article_schema( $data ) {
    // Set the property to true. You can change this to false if needed.
    $data['isAccessibleForFree'] = true;

    return $data;
}
add_filter( 'wpseo_schema_article', 'add_is_accessible_for_free_to_article_schema' );