An operating department may provide services to another operating department of the same State, local government, or Indian Tribe. In these instances, the cost of services provided may include allowable direct costs of the service plus a pro-rated share of indirect costs. A standard indirect cost rate equal to 15 percent of the direct salaries and wages for providing the service (excluding overtime, shift premiums, and fringe benefits) may be used instead of determining the actual indirect costs of the service. These services do not include centralized services that are included in central service cost allocation plans described in Appendix V of this part.