Fiscal stimulus can raise output and incomes in the short run when the economy is operating below its potential. To have the greatest impact with the least long-run cost, the stimulus should be timely, temporary, and targeted. It should be timely so that its effects are felt while economic activity is still below potential; when the economy has recovered, stimulus becomes counterproductive. It should be temporary to avoid raising inflation and to minimize the adverse long-term effects of a larger budget deficit. And it should be well targeted to provide resources to people who most need them and will spend them: for fiscal stimulus to work, it is essential that the funds be spent, not saved...
...The most effective fiscal policy options to stimulate the economy are those that would increase spending quickly and be short-lived. Those criteria can be met by policies that temporarily boost the purchasing power of households who are most likely to increase their spending quickly in response. Extending unemployment insurance beyond its normal twenty-six-week limit, raising food stamp benefits, or issuing refundable tax credits, all on a temporary basis, would likely provide the greatest fiscal stimulus in the shortest time...
...Policies that boost investment, such as direct spending on public infrastructure or tax incentives for businesses, are likely to have a smaller impact on the economy than policies designed to increase consumer spending. In particular, the available evidence suggests that the stimulus they provide would be small, not well-timed, or both.