I have a question about state income tax. If I lived in Maryland for a summer last year and worked in D.C., am I subject to income taxes from either? Or would I be obligated to pay income taxes to the State of which I am a permanent resident, Florida (actually, FL doesn't even have state income tax)? It is nonemployee compensation from a D.C. company.
I've already handled the federal income tax, but I just want to make sure I've squared away any potential state income tax as well.
You aren't required to file a DC return because DC has a reciprocity agreement with all the other states. If you were a nonresident of Maryland, you aren't required to file a Maryland return if you had no income from Maryland sources (see Maryland Nonresident Tax Forms & Instructions for details). As you stated, Florida does not have a personal income tax.