The promotion comes in celebration of National Avocado Day.
To take advantage of the offer, you'll need to log-in or create an account in the Chipotle mobile app or at chipotle.com. After choosing an entree, you can then pick guacamole as an add-on, a side item, or as a regular order of chips and guac. Then, as you complete your order, you'll need to enter the code: "AVOCADO."
Photo by Beth Galton / Chipotle.