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Please refer to the IRS publication 3, Armed Forces' Tax Guide - http://www.irs.gov/pub/irs-pdf/p3.pdf
Generally as you are on active duty - you are taxed based on your home of record. If you were called to active duty out of Maryland - you are considered a resident of Maryland.
Your "state of legal residence (SLR)" is your home of record.
If you was a resident of Maryland , but worked in Alabama - your wages are taxed for both - for Alabama because this is income from Alabama sources and from Maryland - because you were a resident of Maryland.
For Alabama you need to file a tax return as non-resident, and for Maryland you would file as a resident, but to avoid double taxation of the same income - you would claim a credit for taxes paid to Alabama.
If you want to change your state of legal residence (SLR) - you should submit US Department of Defense the form DD 2058 "State of Legal Residence Certificate" - http://www.dtic.mil/whs/directives/infomgt/forms/eforms/dd2058.pdf
Bringing in home of record makes this even more interesting... our home of record is Kentucky. We only lived in Maryland a few months, and we are supposed to go back to Kentucky when we are done here. Do we file non-resident for AL and MD, and resident for KY, with no income?
If you neither life nor work in Maryland - that is not considered an income from Maryland sources - and therefore - this income would not be taxable in Maryland.
If your employer marked in W2 that income as taxable in Maryland - you need to ask about correcting W2.
Please feel free to ask if you need any clarification.