This guidance is a part of the supporting materials for the final Combined Sewer Overflow (CSO) Control Policy. It aids in supporting the establishment of a consistent national approach for controlling discharges through the National Pollutant Discharge Elimination System (NPDES) permit program. This guide presents alternative sources for: capital funding to pay for CSO construction projects; and annual funding to repay annual debt service and operating costs. The guide describes a broad spectrum of funding options, discusses their applicability to CSO control projects, and reviews the benefits and limitations of each option. The guide includes examples that illustrate how permittees are addressing CSO financing.