Find out how to check the Subway gift card balance. The information below shows how to check the balance of your Subway gift card, this includes checking the balance online, by phone or in store. Make sure you have your card number ready along with the pin. All questions or issues regarding your Subway gift card should be directed to the merchant that issued the gift card. It is important to check your gift card balance to verify the amount on your card and that it is not expired.