Self Directed 401K Taxation of Rental Income

[Patrick Hall]

I am looking for some initial advice (prior to hearing from my CPA) concerning the use of a self directed 401k to purchase and operated a multifamily real estate unit.  My primary question is one of "business" or "commercial" rental income tax (currently Ohio State).  I know my taxes from the rental income on a personal level are deferred until retirement but is the unit subject to "business" income tax?  For some reason I believe I heard someone on BP discussing commercial taxes that were unrecognized during their analysis of a property and it significantly impacted the returns.

Thanks in advance for any advice. 

Jimmy Patrick Hall