Tom, that information (your first link) is contrary to what the BATFE FAQ site says in discussing people who own homes in two states, and who occupy one as a vacation home. The FAQ specifically says that you are a resident of each state for the period of time you are living in that state. A vacation home is no less a "home" than a year-round residence as long as the owner occupies the vacation home him/herself and doesn't use it solely as a rental property.
The advisory you're showing doesn't address people with homes in two states of the U.S., it's for people who live outside the U.S. See the instructions for both question 2 and question 13.
The answer to the question in the OP here is the instructions for questions 20a and 20b on the Form 4473. The buyer would show his "other" state driver's license and one of the alternate forms of identification. It doesn't have to be a government-issued ID card, it can be a tax bill. Anyone who owns a vacation home must receive a tax bill, either once or twice a year.
Last edited by Aguila Blanca; July 8, 2013 at 05:09 PM.