It's probably not exactly circled on your calendar, but Tuesday is National Taco Day.

It's an excuse for Mexican food purveyors to either offer cool discounts or come up with another promotion in hopes to catching the attention of hungry diners with myriad options.

Some chains are opting for giveaways or deals for the day. Others, like giants Taco Bell and Qdoba, are going a different route, using it as a day for promotions rather than discounts.

Here's what some of the major chains are doing:

Chipotle Mexican Grill. After trying it in five markets, the big chain is using the day to add chorizo, the spicy Mexican sausage, as an ingredient in its dishes — including tacos.

•Taco Bell. The giant of Mexican food is offering to share National Taco Day greeting cards.

•On The Border. The chain offering 50-cent mini-tacos all day.

•Salsarita's Fresh Cantina. The two taco combo will be $5 for one day only.

•Qdoba. A custom taco-themed Spotify Taco playlist