You can file Maryland state taxes for free on their website regardless of your tax situation as long as your federal tax return has already been completed. (You need the AGI and some other info to complete Maryland.)
In Maryland it's called iFile for Individuals and you can fit it at MarylandTaxes.gov and follow the menus. (Or directly at https://interactive.marylandtaxes.gov/Individuals/iFile_ChooseForm/default.asp).
