Heat oven to 425°F. Line the cookie sheet with sides on foil or cooking parchment paper.
Place frozen potatoes on a cookie sheet. Bake as directed on the bag.
Meanwhile, in a 10″ skillet, cook beef over medium heat for 8–10 minutes, stirring occasionally, until thoroughly cooked; drain. Add taco seasoning mix and water. Cook for about 2 minutes or until hot. Sprinkle potatoes with beef mixture and cheese.
Bake 3–5 minutes longer or just until cheese is melted.