PEOPLE who have deferred the option of early tax preparation are suffering the penalties of procrastination this week. At this point, menu planning is likely to be a matter of deciding between Chinese and pizza carryout. This option, however, may be available only to those in high tax brackets.

For those who choose to cook, meals need to be three things--fast, nutritious and cheap.

Fast, because although concentration improves if attention is diverted occasionally, there is a point of diminishing returns. Nutritious, because you're not only getting a double dose of stress, you're probably losing sleep and skipping exercise. Good nutrition helps to prolong good health in the face of other physical debits. Cheap, because there's nothing like taxes to remind you how tough times really are.

If cooking is out of the question, keep healthful snacks on hand. Nobody's telling you to eat carrot sticks and cucumber slices during tax time, but there are comfort foods that are more nutritious than nacho chips. Peanut butter, cheese, dried fruit and nut mixes, and even bananas are gratifying without being totally devoid of nutrients.

The following meal fits all the requirements, and can be made after a trip through the express lane at the supermarket, provided you have flour, sugar, salt, pepper and butter or oil in the kitchen at home. The shopping calls for canned refried beans, going under the assumption that anyone who has waited until now to prepare taxes probably doesn't have the time to start refried beans from scratch. If the supermarket at your store allows more than eight items, pick up some hot pepper for the tomato sauce. EXPRESS LANE LIST: garlic, oregano, green chilies, tomato sauce, monterey jack cheese, corn tortillas, canned pinto or refried beans, zucchini. MEXICAN PIZZA (4 servings)

This is a mild sauce. You may want to perk it up with jalapeno peppers or hot red pepper sauce. 1 tablespoon oil 1 clove garlic, minced 1/2 teaspoon oregano 4 ounces chopped green chilies 2 cups tomato sauce 2 cups shredded monterey jack cheese 4 ounces canned green chilies, sliced into strips 8 corn tortillas

Heat oil in small saucepan. Add garlic, oregano and chilies. Cook over medium heat until onion softens. Add tomato sauce. Allow it to simmer while you shred cheese.

Set tortillas on baking sheet. Spread with sauce, top with grated cheese. Bake at 350 degrees for 10 minutes.

If you've bought canned pinto beans, mash them in a skillet over medium heat until they reach desired consistency (some people like the beans practically pure'ed, others like them chunky). If you've bought canned refried beans, form them into small patties and heat them on both sides in a little oil. These beans will benefit from the addition of chopped hot peppers.

Pass extra sauce for the beans. Serve with zucchini that has been cut into chunks and steamed with oregano, olive oil, salt and pepper.