Washington ? Flush with extra cash from tax cuts, America’s consumers treated themselves in August and spent with gusto, good news for the economy’s revival.

The Commerce Department reported Monday that consumer spending increased by a strong 0.8 percent last month on top of an even bigger 0.9 percent advance in July as larger paychecks and other incentives from President Bush’s third tax cut began to take hold.

“Consumer spending turned in another stellar performance,” said Wachovia economist Mark Vitner. “Spending continues to be bolstered by the recently enacted tax cuts.”

Americans’ disposable incomes, or what’s left after taxes, advanced by 0.9 percent in August, following a 1.5 percent jump in July.

The government attributed much of the increase in disposable incomes in July and August to the president’s tax cut, which lowered federal tax withholdings, boosting people’s take-home pay.

Commerce Secretary Don Evans said the tax cuts were “helping American consumers keep more of the money they earn” and that “their increased purchasing power is strengthening our economy.”

Excluding the tax impact, disposable incomes increased by a more modest 0.3 percent in July and 0.2 percent in August.

The spending and income figures are not adjusted for price changes.

Consumer spending accounts for roughly two-thirds of all economic activity in the United States. Because of that, the behavior of shoppers is a major factor in shaping the economy’s recovery.

The economy grew at a 3.3 percent rate in the second quarter of this year, and economists are predicting it is now gaining even more momentum.

Many analysts believe the economy is growing at a rate in excess of 5 percent in the current quarter and should be able to maintain growth above 4 percent in the final three months of the year.