Chipotle is giving away free guac for National Avocado Day — but there's a catch

• Chipotle is giving away a free serving of guacamole with entree purchases on July 31.
• To receive the offer, customers must have become Chipotle rewards members by July 30. The offer automatically appears in rewards' members accounts, and is valid through August 2.
• Chipotle is also hosting an "Unlock the Guac" competition, which gives customers the chance to win free guac for a year by guessing the passwords to six specific rewards accounts.

Friday, July 31 is National Avocado Day.

National Avocado Day means that Chipotle is giving out free guacamole to all of its rewards members, the chain announced in a press release emailed to Business Insider.

Chipotle's 15 million rewards members will receive an offer for a free guacamole topping for an entree in their rewards wallet on July 31. Customers had to sign up for the rewards program by Thursday, July 30. The free guac offer will last through August 2 and can't be redeemed via third-party delivery app or catering.

For guac lovers who didn't sign up for Chipotle's rewards program by July 30, all is not lost.

Chipotle is also awarding free guac for a year to six winners in a new "Unlock the Guac" competition. To win, players must guess the password to one of six accounts (there are six ingredients in Chipotle's guac) pre-loaded with a year of free guac offers. Clues will be posted to Chipotle's Instagram, TikTok, and Twitter on Wednesday and Thursday, and players can send their guesses to 888-222.

Chipotle also gave away free guac on last year's National Avocado Day, serving a total of over 800,000 guac sides — the most the chain's ever served in one day.

"National Avocado Day has become a holiday synonymous with Chipotle's fresh, hand-mashed guac without the extra cost," sad Chris Brandt, Chipotle's chief marketing officer, said in the press release. "This year, guac once again isn't extra on Avocado Day and we're giving fans a chance to guess their way to free guac for an entire year."

For more information on the free guac promotion and the "Unlock the Guac" competition, visit Chipotle's National Avocado Day page.