CartRules One Tag in Cart for WooCommerce

This plugin stops customers from mixing products with different tags in the same order. If a product is already in the cart, adding a product with a different tag will either be blocked, or the cart will be emptied first, depending on the option you choose.

This is useful for stores that need to keep certain product groups separate at checkout, for example pre-orders, personalized items, or products fulfilled by a different process.

Once activated, go to WooCommerce > Settings > CartRules > One Tag in Cart to turn the restriction on and choose what should happen.

Works with both the classic, shortcode-based cart and checkout, and the newer WooCommerce Cart and Checkout blocks.