I filed the Partial Year / Non-Residency form in Hawaii,
The above statement is contradictory and makes me think you checked the box on the N-15 for non-resident. If you were a HI resident the first part of the year, then you should have filed a part-year residence return with HI - not a non-resident return. In other words, on the N-15 you should have checked the box for part year resident; not the box for non-resident.
I can't speak for MT forms, because I'm not at all familiar with them.
I'm probably just not being clear I admit I'm no expert. To clarify my N-15 IS checked part year resident. The state rejected my filing and stated my W2 must be updated to reflect apportionment between the two states. My employer does not agree, nor does the Payroll company agree with the states request. I filed the appropriate Montana forms for part year resident. I'm not worried about Montana I've had it reviewed locally and it is correct. Hawaii is my problem. Sorry for being unclear.
The state rejected my filing and stated my W2 must be updated to reflect apportionment between the two states.
While I am familiar with HI state taxes, I'm not all that up on dealing with two states. But for HI, I assume you are submitting via e-file and the HI state computers are rejecting it. In other words, it's not a letter you got from the HI dept of taxation or anything like that.
One thing I don't know yet, is details concerning the W-2. I would expect you have either 1 W-2 from your HI employer from the time you worked in HI< and another W-2 from the MT employer from the time you worked in MT.
One other W-2 possibility is that you have 1 W-2 that shows two states in boxes 15-16 and 17.
So which do you have? Or is it something totally different?