You can google the state laws for obtaining a drivers license in GA by going to the GA site for that yourself--we do not know state laws pertaining to driver's licenses here.
But your BF's driver's license has nothing to do with how he files his tax return unless it causes a problem for him when he wants to e-file a GA return if GA wants a GA driver's license to e-file. (if he does not have one and the state requires a GA ID or license then he will have to mail his GA tax return)
When BF prepares his 2020 tax return he needs to use his current address---the address where he can receive mail from the IRS. He will file a normal federal tax return (ALL of his 2020 income goes on the same federal tax return---so he must make sure he enters the W-2's from the MI employer and the GA employer on the same return) and part-year tax returns for both MI and GA. He will have to pay careful attention as he prepares his tax returns so that he pays MI state tax only for the time he lived in MI and GA for the time he began to live and work in GA. When he is preparing the federal return it will ask about what states in which he earned income and provide a spot to enter the dates. That information will flow over to the state forms.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
