Yes, you may have to file state income taxes in both state but you will be able to take a tax credit in the state where you are considered a permanent resident for taxes paid to your nonresident state.
So if you maintain your permanent residence in MD (you use MD on your driver's license, voting registration, permanent address, etc.), you will need to file a MD resident state tax return. If you are only a temporary resident of IL, then file an IL nonresident state income tax return.
You
will need to file as non-resident for IL (for your IL source income only). You
will also need to file a MD resident state tax return (for all income from all
sources including IL). You will get a state tax credit in MD for any IL state
taxes that you paid on your nonresident IL state tax return.
You
will want to work on your non-resident IL state tax return first. You will then
take a tax credit from your non-resident IL return on your resident MD state
tax return. (Please note that you will only get a tax credit for your IL taxes
up to the amount of MD taxes that would have been paid if the income was earned
in MD).
Just
follow the TurboTax guide when working on your states (remembering to do your
non-resident state return first) and TurboTax will do all the calculations and
credits to your resident states return
Here
is additional information about filing in multiple states (select "see
entire answer" to view the entire attachment)
https://ttlc.intuit.com/replies/3300797
