Coupons give members a free add-on book in their box. Members have to ship a monthly selection and add at least one more book to take advantage of a coupon.
Coupons are only visible in your box upon adding at least 1 book.
Coupons can only be redeemed in the month they are active and expire at the end of the month if not used. However, if you have multiple coupons on your account, only one will be available at one time and the other ones will roll over to the following months.
You get a coupon if you are a BFF and it's your birthday month or if you purchase a 6 or 12-month gift during holiday promotional periods.