Operating costs shall be reduced by the cost of services and activities which are not properly chargeable to patient care. In the event that the commissioner determines that it is not practical to establish the costs of such services and activities, the income derived from them may be substituted for their costs. The activities and services covered by this provision include, but are not limited to:
N.Y. Comp. Codes R. & Regs. Tit. 10 §§ 86-4.22