"And then IL will not grant a resident credit for taxes paid under the convenience of the employer rule, because it views the income as IL-source and the other state as having an invalid tax claim."
Can you cite an official source for that statement?
IMO, all that is required for a taxpayer to be eligible for the credit is that the income is taxed by two states (as per the Supreme Court ruling).
And, for what it's worth, NY's "convenience" rule has been challenged in court - unsuccessfully.
https://law.justia.com/cases/new-york/court-of-appeals/2003/2003-18774.html
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
