Colombia is facing a fiscal situation featuring large and probably unsustainable projected deficits. The solution will almost certainly involve some combination of increased tax revenues and decreased expenditures. Tax revenue increases can come from either raising the rates or expanding the base of existing taxes, introducing new taxes, or increasing the effectiveness of how existing are enforced. In this sense, taz rate increases and enforcement increase are substitutes. In determining the proper mix of policy, the standard tools of public finance ca have much to say.