Allow cream cheese to soften (or soften for 30 seconds in the microwave), add sour cream and taco seasoning, and blend with a mixer on low. Spread mixture into a 10X13 cake pan, or similar flat container. I prefer to let this sit overnight in the fridge (covered), but it is not necessary.
Shred the other ingredients, and layer them on top of cream cheese mixture any way you prefer, and in any amounts you prefer.
Open a bag of Tortilla chips, and you're done! Stays fresh in the fridge (covered) for up to a week if you have any leftover!