Here's how to use Coupon Code when shopping in Subway: add new products to the Subway shopping cart and click the checkout. Log in or create a new account to Subway by entering details, then click Continue to pay. Below the listed items, you will see a box that says Add Coupon, choose the Subway Coupon Code you are going to use and then the website will automatically return to the checkout page. Now you will see your actual total payment at subway.com.au.