You pay in-state tuition at a New Mexico state-funded school if you are on active duty and permanently stationed in New Mexico, and so do your dependents. If you are reassigned out of state, your dependents keep the in-state rate as long as they stay continuously enrolled and in good standing.
Give the admissions or veterans office at your school a copy of the orders assigning the service member to New Mexico.
Military orders showing a permanent assignment in New Mexico, and proof of dependency for family members.