12. (1) The provisions of this section are prescribed as rules for making findings relating to operating costs. (2) The following rules relate to “base year” and “reference year”: 1. “Base year” and “reference year” refer to certain annual accounting periods established for the purposes of an application. The accounting periods must each be one year in length. The reference year is the period ending immediately before the base year. 2. If the application is by the landlord, the reference year and base year shall be the annual accounting periods most recently completed on or before the day that is ninety days before the effective date of the first rent increase applied for. 3. If an order has been made under the Act increasing the maximum rent for a rental unit by more than the guideline, the annual accounting periods mentioned in paragraph 2 shall begin and end on the same days of the year as the prescribed periods for which information concerning operating costs was filed under clause 53 (a) of the Act with the application that gave rise to the order. 4. If the application is by the tenant, except as provided in paragraph 5, the reference year and the base year are the calendar years preceding the date the application is made. 5. If the application is by the tenant and an order has been made under the Act increasing the maximum rent for a rental unit in the complex by more than the guideline, the reference year and base year shall be the two years that would be determined under section 6 for a notice whose effective date of rent increase is the same as the date of the tenant’s application. (3) The following rules apply to the allocation of operating costs for a residential complex that is part of a larger project if the complex shares those costs with other parts of the project: 1. The operating costs for the project shall, subject to paragraph 2, be allocated among the parts of the project in accordance with one or more of the following factors, i. the area of each part of the project, ii. the assessment for municipal taxes for each part of the project, iii. the market value of each part of the project, iv. the revenue generated by each part of the project. 2. If the allocation of operating costs in accordance with paragraph 1 would be unreasonable considering how much of the costs are attributable to each part of the project, the operating costs shall be allocated among the parts of the project in reasonable proportions according to how much of the costs are attributable to each part of the project. (4) The following rules apply to the situation in which a rent officer decides that an increase in maximum rent should be decreased or the rent or maximum rent reduced because of an extraordinary decrease in operating costs and then considers, under subsection 13 (9) or 24 (3) of the Act, evidence concerning an extraordinary increase in operating costs: 1. The rent officer may deduct an amount in respect of the extraordinary increase in operating costs from the amount of the decrease or reduction that the rent officer has decided upon, but only to the extent of eliminating that decrease or reduction. 2. This subsection does not apply to an application based on an extraordinary increase in operating costs. O. Reg. 375/92, s. 12.