For the typical taxpayer, it tends to be logical which state return you need to file. It depends on where you lived and where you earned or made the money. However for the military service member and their spouse, it’s more complex.
As a member of the military, when filing state returns, you first need to be sure of your state of legal residence (SLR) which is usually your Home of Record. That will be your resident state.
The Service Member Civil Relief Act states that an active duty member is not considered a resident of a state unless it is his SLR.
Each state decides whether service members must file a return when they are stationed outside their resident state. Each state maintains websites with information for active duty military filing in the state.
As an active duty service member, if you worked a non-military job while stationed outside your resident state, you’ll need to report those wages on a nonresident tax return to that state. If you are also filing your resident return, you may get a credit on it for the taxes paid on your nonresident return. We've got some examples.
Due to the Military Spouse Residency Relief Act (MSRRA), a nonmilitary spouse of a service member may be able to keep the same resident state of the military service member regardless of which state they live in. We've got details and examples of how this works.