47 C.F.R. § 64.901 : Telecommunication — FEDERAL COMMUNICATIONS COMMISSION — COMMON CARRIER SERVICES — MISCELLANEOUS RULES RELATING TO COMMON CARRIERS — ALLOCATION OF COSTS — Allocation of costs

(a) Carriers required to separate their regulated costs from nonregulated costs shall use the attributable cost method of cost allocation for such purpose.
(b) In assigning or allocating costs to regulated and nonregulated activities, carriers shall follow the principles described herein.
(1) Tariffed services provided to a nonregulated activity will be charged to the nonregulated activity at the tariffed rates and credited to the regulated revenue account for that service. Nontariffed services, offered pursuant to a section 252(e) agreement, provided to a nonregulated activity will be charged to the nonregulated activity at the amount set forth in the applicable interconnection agreement approved by a state commission pursuant to section 252(e) and credited to the regulated revenue account for that service.
(2) Costs shall be directly assigned to either regulated or nonregulated activities whenever possible.
(3) Costs which cannot be directly assigned to either regulated or nonregulated activities will be described as common costs. Common costs shall be grouped into homogeneous cost categories designed to facilitate the proper allocation of costs between a carrier's regulated and nonregulated activities. Each cost category shall be allocated between regulated and nonregulated activities in accordance with the following hierarchy:
(i) Whenever possible, common cost categories are to be allocated based upon direct analysis of the origin of the cost themselves.
(ii) When direct analysis is not possible, common cost categories shall be allocated based upon an indirect, cost-causative linkage to another cost category (or group of cost categories) for which a direct assignment or allocation is available.
(iii) When neither direct nor indirect measures of cost allocation can be found, the cost category shall be allocated based upon a general allocator computed by using the ratio of all expenses directly assigned or attributed to regulated and nonregulated activities.
(4) The allocation of central office equipment and outside plant investment costs between regulated and nonregulated activities shall be based upon the relative regulated and nonregulated usage of the investment during the calendar year when nonregulated usage is greatest in comparison to regulated usage during the three calendar years beginning with the calendar year during which the investment usage forecast is filed.
(c) A telecommunications carrier may not use services that are not competitive to subsidize services subject to competition. Services included in the definition of universal service shall bear no more than a reasonable share of the joint and common costs of facilities used to provide those services.

47 C.F.R. §64.901

52 FR 6560, 3/4/1987, as amended at 52 FR 39534, 10/22/1987; 54 FR 49762, 12/1/1989; 62 FR 45588, 8/28/1997; 67 FR 5702, 2/6/2002