CAFs have been discussed as a new mechanism for financing federal capital assets. As envisioned, CAFs would have two goals. First, CAFs would potentially improve decision making by reflecting the annual cost for the use of capital in program budgets. Second, they would help ameliorate at the subunit level the effect of large increases in budget authority for capital projects (i.e., spikes), without forfeiting congressional controls requiring the full cost of capital assets to be provided up-front. Through discussions with budget experts and by working with two case studies, the Departments of Agriculture and of the Interior, we are able to describe in this report (1) how CAFs would likely operate, (2) the potential benefits and difficulties of CAFs, including alternative mechanisms for obtaining the benefits, and (3) several issues to weigh when considering implementation of CAFs.