Financial considerations for treatment marshes are comprised of several factors. The actual costs incurred on operating projects consist of capital costs and operating and maintenance costs. In the process of marsh design, cost estimation is a key task. And, it often useful to consider the life costs of the project, whereby capital and operating costs are brought together in a present worth analysis. Financial benefits of a marsh project are certainly considerable, but very hard to quantify monetarily. To complicate matters still further, there are significant differences among the three major types of treatment marshes, surface water and wastewater polishing, urban runoff treatment, and agricultural runoff treatment. Because of the changing value of money over time, there is ambiguity about the value of the dollar. In this chapter, values are adjusted to 2018, unless otherwise stated or implied.