WASHINGTON -- The economic impact from Hurricane Katrina will wipe out 400,000 jobs, cost consumers 40 percent more for gasoline this month and slash previous estimates for growth this year, a hastily prepared report by the nonpartisan Congressional Budget Office concludes.

Stressing that there are still major unknown factors, such as how long it will take domestic oil production to resume along the Gulf Coast, the CBO report released yesterday predicts that the inflation-adjusted growth of gross domestic product -- the broadest measure of the nation's economy -- will slip to 2.7 percent from a previously estimated 3.7 percent.

It calls the reduction in growth "significant but not overwhelming" and notes the impact could be less, with growth closer to 3.2 percent if energy production resumes sooner than expected. The region produces 15 percent of the nation's natural gas supply and about half of that already has been restored.

CBO Director Douglas Holtz-Eakin noted that the economy eventually would benefit somewhat from the disaster as businesses and individuals start working to clear the devastation and rebuild. Every new housing start adds $200,000 to the GDP, so if 100,000 new homes are built in Katrina's wake, that will raise growth $20 billion, or two-tenths of a percent.

But in his letter to Senate majority leader Bill Frist, R-Tenn., Holtz-Eakin stressed that the loss of life and human misery was by far the most serious impact of the storm and its aftermath and that numbers couldn't be assigned to such a shock.

The CBO report notes that, unlike Hurricane Andrew in 2002, the rebuilding will start later because it will take months just to deal with the flooding in New Orleans, where 80 percent of the city was under water.

It said the job loss would have been higher -- as many as 729,900 people no longer are working because of storm damage -- save for the eventual new construction, which will boost the need for construction workers and a range of goods and services, from plywood and concrete to engineering and finance, that will accompany the effort.

The impact on the federal budget, already facing an estimated $333 billion deficit this year, is still unclear but is likely to be costly. In addition to the $10.5 billion already allocated by Congress for disaster relief, another $51.8 billion was requested by the White House yesterday.

Of that, $50 billion is for flexible spending by the Federal Emergency Management Agency, $1.4 billion is for the Department of Defense emergency operations and $400 million is for the Army Corps of Engineers.

"This will not be the last request for emergency funds. We will need substantially more," stressed Joshua Bolten, director of the White House Office of Management and Budget.

Bolten said the money requested yesterday will be enough for the next few weeks and that the projected deficit for the next fiscal year likely will be higher. But as long as there is "good economic growth" in the future, he said, President Bush still expects to cut the deficit in half by 2009.

FEMA, which has been spending $2 billion a day, will give $2,000 debit cards to stranded evacuees without insurance or any means of survival, such as those in the Houston Astrodome and other shelters. Bolton estimated as many as one million people may get the cards.

One grim note, CBO analysts said, is that the federal flood insurance program's reserves may not be enough to pay all the claims that will pour in. That would mean Congress would have to appropriate more money for it as well as for the federal crop insurance program.

Thousands of acres of agricultural land in the affected states have been ruined, as well as oil production, port infrastructure and fishing industries.

While the Port of Southern Louisiana has been badly damaged, most shipping will resume by October elsewhere on the Mississippi River, the CBO report said. Only one grain elevator has been put entirely out of commission, and as power is restored, most elevators are expected to resume operations.

In addition to higher-than-expected federal payments because of the disaster, local, state and federal tax receipts are expected to be down, reflecting incomes lost to the disaster as well as a decline in gas consumption, and thus tax receipts, because of the higher prices.

The Internal Revenue Service has ruled that hurricane victims in Louisiana and in parts of Mississippi, Alabama and Florida may delay estimated payments of individual and corporate income taxes due Sept. 15 until at least Oct. 31 and probably later. Companies with financial records in the region and tax practitioners there also qualify.

The impact on commercial insurance firms currently is estimated at $30 billion, the CBO report said. That compares with the $32.5 billion paid out by private insurance firms after the 9/11 attacks, a significant portion going for business interruption insurance payments.

A second report yesterday from the Federal Reserve Board found that the economic climate had improved until Katrina struck. Whether the Fed will raise interest rates as had been expected when they meet next on Sept. 20 is unknown, although many think that is now unlikely.