In a 6 quart slow cooker, add thawed chicken in a single layer. Add taco seasoning and toss to coat. Top chicken with salsa in an even layer. Cover with lid.
Cook on low for 4 to 5 hours, or on high for 2 ½ to 3 hours, or until chicken shreds apart with a fork (time will depend on thickness of chicken). Shred all of your chicken, stir to combine with salsa.
Serve hot on flour or corn tortillas with your favorite taco toppings.
Notes
If chicken is stacked in multiple layers in a smaller slow cooker, it may take longer to cook in the middle. A single, even layer is best.
Leftover chicken will keep in a sealed container in the refrigerator for 3-4 days, or up to 3 months in the freezer. Reheat leftovers in the microwave, lightly covered with a damp paper towel, until just heated through.
For milder tacos: use mild salsa and the listed amount of taco seasoning.
For spicy tacos: use hot salsa and add up to double the taco seasoning.