Best way to rent to son

[Ben Givens]

My wife and I are buying our first investment property. Our son will be living there to attend medical school over the next four years. It's a four bedrooms house, and he has already found three roommates each of who will pay $500 rent. Should our son also pay rent? Most rentals in the area go for $1500- $2500 so with or without his rent, we think it would fall into a "fair market value". However, from the IRS pub. 527, under personal use, example 3 says that if he pays rent than its not considered personal use implying that if he doesn't then it would be. We don't want to do the messy calculation of cutting his portion out of deductions and depreciation, but we also prefer not to have to claim as income money he would pay as rent (especially because we would likely be providing that money). Can someone give us advice. Thanks.