AMERICA’S long-run fiscal outlook is bleak, mostly because of an aging population and rising health care costs. To close the gap between expenditures and revenue, we’ll likely see a combination of revenue increases and spending cuts. And we’ll need to focus especially on reducing spending, largely because that taxes on the wealthy can be raised only so high.

Consider the tax burden on high earners once the Bush administration’s tax cuts expire next year. Add up the federal, state, city and sales taxes for a lawyer in New York City who earns $300,000 a year. Depending on the circumstances, this individual could be facing marginal tax rates in the range of 60 percent. Higher income tax rates would discourage hard work and encourage tax avoidance, thereby defeating the purpose of the tax increases.

The most potent way to add revenue is to impose a value-added tax. As its name indicates, a V.A.T. takes some percentage of the value added at each stage of production. V.A.T.’s raise money so readily and so invisibly that they often climb to a range of 15 to 20 percent; politicians like the revenue, and voters don’t always notice the burden.

A move toward a V.A.T., however, also brings price inflation, a big increase in the tax-collecting bureaucracy and the emergence of favored sectors with exemptions or lower rates. Though we may well end up with a V.A.T., it isn’t obviously the best option.