The revenue of a center should be offset only by the related variable costs and by those fixed costs that are directly traceable to the center Common fixed costs-- those that jointly benefit several profit centers should not be allocated among the centers deriving benefit Thus, the responsibility income statement includes only those costs directly traceable to the center's activities. Furthermore, traceable fixed costs may be divided into the subcategories of controllable fixed costs and committed fixed costs. This enables the responsibility income statement to show as a subtotal (performance margin) those aspects of the center s operations that are readily controllable by the center manager.