Determine if you qualify for residency based on where your parents live. If you are under the age of 21, then your residency is the residency of your father. If your father is deceased, then it reverts to your mother. If your parents are divorced, then your residency is that of your custodial parent. Finally, if you survived both parents, then your residency is that of your last surviving parent or appointed legal guardian.
Prove that you are an official resident of Mississippi. Students who are 21 and over must live in Mississippi for 12 continuous months before attending school and receiving the benefit. Ways to prove this are filing a Mississippi state income tax return, registering to vote within Mississippi, providing proof of employment within the state, a Mississippi driver's license or a military Home of Record. Note, that a rental agreement and utility bills are not proof of residency.
Determine if you qualify for an exception. There are two main exceptions. Married couple's may use the residence established by their spouse or establish residency independently. Also, active military personnel who are on extended duty within the state qualify for residency. Additionally, their spouses and children qualify as well.
A person may still qualify as a resident of Mississippi after a temporary absence from the state. Military service, school attendance or an out of state job are all valid reasons for a temporary absence as long as you can show an intent to return to the state as your primary residence. This includes students of military parents who are under 21 and whose parents are stationed overseas.