Chris Woodyard

USA TODAY

Corrections & Clarifications: To correct story to note Salsarita's Fresh Cantina did not offer a promotion for National Taco Day in 2016.

It's probably not exactly circled on your calendar, but Tuesday, Oct. 4, 2016, 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.

Some chains are thinking big. Margaritas Mexican Restaurant, a 26-unit chain, plans not only to add a two-pound taco to its menu but offer a free regular taco to the deal.

“Last year’s two-pound Taco Gigante promotion was such a hit that we knew we had to do something extra special this year,” said Margaritas President Hugo Marin. Giving away a free regular taco with its monster "allows our guests to see for themselves the difference in size, further adding to the excitement around our National Taco Day celebration.”

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.

•El Fenix. The 23 restaurants in the Mexican chain founded in 1918 in Dallas will offer a design-your-own taco plate for $4.98. The deal is good through Sunday with a coupon.

•Rubio’s Mexican Grill. The original fish tacos are $1.75 on Tuesday.

•Del Taco. The day just happens to fall on a Tuesday, when its regular crispy-shell tacos are three for $1.29 from 3 to 11 p.m.

•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.

•Green Leaf’s Beyond Great Salads. The quick-service restaurant is giving away a Baja Street Taco with a $5 purchase.

•Margaritas Mexican Restaurant. A free regular taco to anyone who orders the two-pound Taco Gigante on Tuesday.

•Qdoba. A custom taco-themed Spotify Taco playlist