The Low-Income Housing Tax Credit (LIHTC) program has been a significant source of new multifamily housing for a quarter century, producing more than 2 million units of affordable rental housing since 1987. In recent years, LIHTCs have provided funding for approximately one-third of all new multifamily housing units built in the United States. In the past few years, however, thousands of properties financed through LIHTC have become eligible to leave the program, ending rent and income-use restrictions. In the worst-case scenario, more than 1 million LIHTC units could leave the stock of affordable housing by 2020, a potentially serious setback to the goal of expanding housing choices for low-income households.