With few exceptions, professional planners recommend retiring with no debt. Yet the share of households over age 65 with debt is up sharply since the late 1980s. The debt picture looks poised to deteriorate further for the coming generation of retirees: Gen X. The oldest Gen Xers are 60 years old, and by several measures they’re deeper in debt than other generations. For our series “Buy Now Pay Later,” senior economics contributor Chris Farrell explains.