That’s not the case in California. For starters, the California Department of Tax and Fee Administration (CDTFA) distinguishes cold sandwiches from hot sandwiches. Sandwiches categorized as “hot prepared food products” are subject to California sales tax unless otherwise exempt. By contrast, sandwiches not “intended to be in a heated condition when sold” are not hot prepared food products and so generally are exempt.
Hot prepared sandwiches include grilled sandwiches, dipped sandwiches (e.g., the French dip, which comes with hot gravy), and sandwiches heated by infra-red lights, steam tables, and other means. A toasted sandwich intended to be consumed while warm is considered a taxable hot prepared sandwich even if it’s room temperature when served. However, a cold tuna sandwich on toast isn’t considered a hot prepared food even though the bread may be toasted.
The CDTFA doesn’t reference burritos on food tax bulletins, but burritos do pop up in publications for California liquor stores. Apparently, many liquor stores in California have microwave ovens used to heat food products such as burritos.
If the microwave oven is accessible to customers, it’s assumed the consumer would microwave the frozen burritos, so the burrito isn’t taxed: The food isn’t prepared for the customer; the customer prepares the food themselves. Yet if the microwave oven is accessible only to store employees, the sale is considered a sale of prepared food and is therefore taxable.