What do you call the method that allocates costs by explicitly including all the services rendered among all support departments?

The method that allocates costs by explicitly including all the services rendered among all support departments is called the "reciprocal method" or "reciprocal allocation method." This approach recognizes the interrelationships between support departments and allocates costs based on the services exchanged among them, providing a more accurate reflection of their true costs. It typically involves solving a system of linear equations to determine the final cost allocations.