I worked in Illinois and retired to Arizona at the end of 2016. I was granted RSUs by my Illinois employer over the years and a portion of the granted shares vested in 2017 (this will also occur in 2018 and 2019 since any grant is vested in thirds). My employer reported this as W-2 income and withheld taxes (I understand how that works). The State tax withholding was assigned to Illinois (not Arizona). I was not a resident of Illinois at any time in 2017. Do I simply file a non-resident Illinois Tax return and get the refund of the withheld amount or does Illinois still have a claim to the taxes since the grant occurred while residing in Illinois even though I was no longer a resident when the subsequent taxable vesting event occurred (I have heard elsewhere that some states do this)? Note that there is no entry in Box 14 of the W-2 indicating RSU.
