@Zbucklyo Thank, you, I actually went to check their website.
Here it says "You are an Illinois resident if you were domiciled in Illinois for the entire year."
I was not in IL for the whole year, but it doesn't say "if and only if you were domiciled".
So I looked for more and I found the following:
<a rel="nofollow" target="_blank" href="
https://www2.illinois.gov/rev/individuals/filingrequirements/Pages/default.aspx">https://www2.illino...>
An Iowa, Kentucky, Michigan, or Wisconsin resident who worked in Illinois, must file an Illinois tax return if:
1) you received income in Illinois from sources other than wages, salaries, tips, and commissions,
2) you want a refund of any Illinois Income Tax withheld.
If you received wages, salaries, tips, and commissions from Illinois employers, you are not required to pay Illinois Income Tax on this income.
So it sounds like if my 2 year job assignment still counts me as a Michigan resident, then my employer may have been fine to charge my W2 tax under Michigan instead of Illinois?
