Owner occupied multifamily?

[Jack Forester]

Okay, here's the scenario.  Just bought a 4 unit multifamily property (one tax parcel with 3 buildings).    It's got a 2 bedroom unit, a 1 bedroom unit, and a duplex.  My son (in college) will be living in the 2 bedroom for the next 2 years with a roommate. The roommate is paying rent.   The 1 bedroom is rented and the duplex is fully rented.

1) Does my son living there make it be considered "Owner occupied" for tax purposes? Does it make a difference, if I charge him rent?

2) If this is considered "owner occupied", and I have to do the portion-of-the-whole accounting (approx 20% of the total property would not be deductible), what happens in 2 years when my son moves out, and I fully rent out the 2 bedroom unit?  Obviously, expenses are fully deductible, but what happens with depreciation?  If I'm calculating depreciation, then only claiming 80% for the first 2 years, after that I'd start deducting the full amount, but in 27.5 yrs, I'd still have leftover basis of 20% of the first 2 years depreciation, right?  Is that even a problem?  I guess maybe that's always the case, because if 10 years into owning a property, I put a new roof on, that's depreciated over the next 27.5 years from the date installed.

Assuming I'm correct about #2, then my only question is #1.  Is a family member occupied room considered owner-occupied?  My guess is "yes".