1st time dealing with income from multiple states

[75Mopar]

My son started work as a mill right for multiple companies. Now most of the companies are based in other states (he lives in Maine) but I believe all of the work he did for them was in Maine except for 1. It was the one day he worked in New Hampshire.

Using TurboTax I entered all of the W-2's and now I'm at the state portion. Since he worked in New Hampshire and they don't have state taxes I do not have to file a return for New Hampshire correct?

One thing I just noticed is that in box 15 it lists PA with a state ID number and boxes 16 and 17 have dollar values. The company is based in PA, but he did not work in PA so now I'm not sure what to do.

[Vanessa A]

Correct, he does not have to file a NH return because NH does not have a state tax.

For PA, he will need to file a return and mark the Non-Resident Box, and then while walking through the steps, you will be able to allocate income to PA.  You will need to add $0 income to PA and the full amount of withholdings so he can get a refund of that amount.

Then he will need to file a Maine return as a resident and include all income from all sources since he lives and works in Maine.  If no taxes were withheld for Maine, then he will likely need to submit payment with his ME return.  

He should contact his employer to  let them know that he is not living (they should know he is not working in PA) and ask them to withhold taxes for ME instead of PA. 

Although PA is a convenience of the employer state, one of the exceptions to that is the employer needs them to be where they are to access customers or other specialized tasks, if he is doing the work for multiple companies in ME, then that would qualify for the exception to the convenience of the employer rule. 

Do I need to file a nonresident return for an out-of-state employer?