I am a grad student in Maryland and rent a house in Maryland, where I reside 9 months of the year for school. In the absence of school and during breaks, I return to my parent's home in Virginia, where I maintain my driver's license and voter registration. However my parents do not claim me as a dependent (I support my own living costs at school). What residency status do I file for each state?
I consider Virginia my permanent residency and filed a resident return there. Is that correct?
However Maryland has a domiciliary resident clause where maintaining a place of abode for 183 days counts you as a resident. Does renting a (not a dorm and not university owned) house for the purpose of school count me into this category?
To complicate things, I understand Virginia and Maryland have a tax reciprocity. But I am not sure it applies if I have to file resident return in both states.
What residency status do I file for each state and will I get double taxed?
It appears that you have a situation of dual residency. You are a domiciliary resident of VA and a statutory resident of MD. As such, you must file as a resident in each of the two states.
The MD-VA reciprocity agreement does not apply to statutory residents of the non-domiciliary state, but you may qualify to claim an "other state credit" on your VA return. See "dual residency" in this Viriginia tax reference:
For Maryland's rules on tax residency, see this: