As I noted in my answer, I do not think the question of residence is clear one way or the other and could see courts ruling in either direction with justification. It becomes interesting when you look at how the state itself treats questions of residency for income tax purposes. Persons living in Illinois on a temporary or transient basis are not residents and Illinois residents living temporarily or as transients in another location remain Illinois residents.
Originally Posted by Eric Johnson
Temporary or transitory purposes. Whether or not the purpose for which an individual is in Illinois will be considered temporary or transitory in character will depend upon the facts and circumstances of each particular case. It can be stated generally, however, that if an individual is simply passing through Illinois on his way to another state, or is here for a brief rest or vacation, or to complete a particular transaction, or perform a particular contract, or fulfill a particular engagement, which will require his presence in Illinois for but a short period, he is in Illinois for temporary or transitory purposes, and will not be a resident by virtue of his presence here. If, however, an individual is in Illinois to improve his health and his illness is of such a character as to require a relatively long or indefinite period to recuperate, or he is here for business purposes which will require a long or indefinite period to accomplish, or is employed in a position that may last permanently or indefinitely, or has retired from business and moved to Illinois with no definite intention of leaving shortly thereafter, he is in Illinois for other than temporary or transitory purposes, and, accordingly, is a resident taxable upon his entire net income even though he may also maintain an abode in some other state.There is no fixed definition or the length of an assignment that would qualify as permanent rather than temporary. Similarly, in defining domicile, the state places great weight on long term intent. If a person owns a residence, has lived in it, and leaves it for a period of time with the intention of returning ultimately, the residence remains their domicile whether or not they live in it during a particular period. Thus, a temporary lease of a house would not mean that house is no longer a domicile for the owner unless it were done in a manner that made it clear that the long term intent was to leave.
Obviously, accepting a potentially multi-year temporary assignment in Washington pushes the limits. However, I don't think there was ever any question that Rahm was a resident of Chicago before going to Washington, that his work in Washington was temporary in nature, and that his long term intention was to remain a Chicago resident and return on conclusion of his work in the White House.
The courts will have to make a judgment based on the facts of the specific case. However, the law does not clearly dictate what that judgment would be. This is clearly what is also said in the "expert" comments made in the articles you cited. It could go either way and will depend on fuzzy questions such as evidence of intent, and not simply be answered by physical location during the prior year or by the fact that the house was leased to someone who would like to stay there.