I would assume that you are married because you have a valid license. However, there is a question if the Supremes uphold the Utah ban. Your better bet would be to go to California and get married there. Having said that, you still will not be able to file a joint return in Idaho for Idaho taxes, only for Federal. I am not aware of any other taxes that would be different because you are married. Also, in Idaho I do not believe that community property rules would apply to you yet, so it would still be a good idea to have property titled as joint tenants in case one of you dies. You also need to make sure your wills and powers of attorney name the other person. You should talk with a local attorney about those issues.
Answered on Jan 10th, 2014 at 9:48 AM