My brother and I want to buy a house for cash as tenants in common. He has more cash, so would own 70%, while I would own the other 30%. I would like to live in the house with my wife and family. My brother does not want/need me to pay rent to him – he just wants the equity stake in the house. Do I HAVE to pay rent to him for his greater share? If we agree to have no rental agreement, will the IRS consider this a gift and come after my brother for?