For years, Congress has preferred to use tax incentives rather than direct spending to encourage investment. Thus, while a home buyer may not care whether she gets a tax credit or a check from HUD, for example, Washington seems to have concluded that the tax subsidy is good while the check from HUD is bad. Never mind that both are, in reality, spending. This bit of political ledgerdemain has made it increasingly difficult for lawmakers to choose the most efficient way of delivering subsidies. But surprisingly, the current economic mess may be bringing some clarity to this issue.