The general rule of thumb, especially when it comes to taxes, as well as some government benefits, is this:
If it's not in writing, then it did not occur.
Period.
You would need something in writing, that would be recognized in a court as legally binding, to prove that what you say is your primary residence, is "in fact" your primary residence. The two most common things I'm aware of off the top of my head, is the address on your driver's license, and the address on your voter registration card.
