Allocation of Shared Costs: A Set of Axioms Yielding a Unique Procedure

Often when several goods or services are produced by a common process or organization some estimate of the per-unit costs of these goods is required. In this note we consider cost allocation procedures and show that there is exactly one such procedure which possesses four desirable properties. Both the methods and the result were inspired by the recent work of Aumann and Shapley on nonatomic games.