"The Low Income Housing Tax Credit (LIHTC) represents a novel tax expenditure program that employs "investable" tax credits to spur production of low-income rental housing. While it has grown into the largest source of new affordable housing in the U.S. and its structure is now being replicated in other programs, the LIHTC has also drawn skepticism and calls for its repeal. This paper outlines a conceptual framework for exploring the conditions under which investable tax credits may be the most effective mechanism to deliver a production subsidy and discusses the desirability of employing investable tax credits in other policy domains. Estimates of tax expenditures under this program are provided and efficiency costs, distributional issues, and the likely effects of reforms to tax provisions such as the AMT are considered"--National Bureau of Economic Research web site.