181.08 RENTALS.
   Rental income received by a taxpayer shall be included in the computation of net profits from business activities under sub-paragraphs (c), (d), (e), (f), and (g) of Section 181.03, only if and to the extent that the rentals are derived (whether so rented, managed or operated by a taxpayer individually or through agents or other representatives) constitutes a business activity of the taxpayer in whole or in part.
   Where the gross monthly rental of any and all real properties, regardless of number and value, aggregate in excess of $125 per month, it shall be prima facie evidence that the rental, ownership, management or operation of such properties is a business activity of such taxpayer, and the net income of such rental property shall be subject to tax; provided that in the case of commercial property, the owner shall be considered engaged in a business activity when the rental is based on a fixed or fluctuating percentage of gross or net sales, receipts or profits of the lessee, whether or not such rental exceeds $125 per month; provided further that in the case of farm property the owner shall be considered engaged in a business activity when he shares in crops or when the rental is based on a percentage of the gross or net receipts derived from the farm, whether or not the gross income exceeds said $125 per month; and provided further that the person who operates a licensed rooming house shall be considered in business whether or not the gross income exceeds $125 per month.
(1969 Code 92.08)