Posted on March 9, 2018April 6, 2018 by Rhonda Costco Coupon Book: March 15, 2018 – April 8, 2018 3/9/18. Costco.com just released the March 2018 Coupon Book! Yay!! Earn cash back through the ibotta app, when you shop for certain items at Costco. For more information, check out -> https://ibotta.com/r/mberxtx.