As tens of thousands of families and businesses struggle to rebuild after Hurricane Katrina, many of them will find themselves not only without homes, cars and other possessions but also without the paper and perhaps even electronic records and resources fundamental to the working of American life and commerce.

For many, the entire economic structure on which they are accustomed to running their lives has been torn away. How do you get a credit card bill, let alone pay it, when your house is gone, your very address is gone, your bank's offices are gone?

At least in the short run, though, government agencies including the Internal Revenue Service, mortgage companies such as Fannie Mae and Freddie Mac and even some credit card issuers are offering relief to those hurt by Katrina.

The IRS, for example, has extended various deadlines, such as that for estimated tax payments normally due Sept. 15, until Oct. 31 and has waived late-filing or late-payment penalties that would otherwise apply. An agency spokesman said the IRS has set up a task force to try to work out other forms of assistance that might benefit taxpayers in the afflicted areas.

The U.S. Postal Service is focusing on getting Social Security checks to recipients and has set up mobile facilities in Louisiana and Mississippi "for people to be able to come and get their Social Security checks," USPS spokesman Gerry McKiernan said. The USPS is also setting up a "New Orleans" post office at the Astrodome in Houston, where many hurricane refugees have been taken, McKiernan said.

The Social Security Administration is also allowing beneficiaries, many of whom are far from their mailing addresses, to go to any local Social Security office, verify their identities and receive checks on the spot.

Electronic direct deposit should have been uninterrupted, SSA spokesman Mark Lassiter said, but beneficiaries who are unable to get to their banks or are without debit cards can also get immediate payment from a local Social Security office.

Fannie Mae and Freddie Mac have both said they are offering relief to homeowners hit by the storm. Freddie Mac is also expediting release of insurance proceeds, on which mortgage holders normally have a claim, so that homeowners will have money to begin repairs.

Both companies said relief will be offered case by case. Neither company issues mortgages, but both buy billions of dollars in mortgages from loan originators and thus have authority to ease payment terms on those loans. Borrowers need to contact their servicers, which can usually be identified from payment coupons or other documents concerning payments, and ask who owns their loans and whether relief is available.

Credit card issuers are not required to grant relief -- "It's really up to individual banks," said Sharon Gamsin of MasterCard Inc. -- but in disasters, many have.

Capital One Financial Corp. of McLean said it has "put our emergency services into action which includes some flexible payment options" for cardholders. The company said it is also looking for alternate ways of communicating with customers whose mail cannot be delivered.

David Robertson, publisher of the Nilson Report, which covers the industry, said card companies granted relief after the recent Florida hurricanes and find it in their interest to do so.

"In this day and age when credit card customers are hard to come by, you want to make sure you make the effort to retain the ones you've got," Robertson said. " . . . Customers who are affected are walking around with multiple cards in their pocket and the last thing any of those [card companies] want to do is put themselves at a disadvantage versus their competitors."

But despite all this relief, the outlook for many families and businesses in the area hit by the hurricane is for a long and difficult recovery.

Much of the damage was and is being caused by flooding, a peril that is not covered in normal homeowners insurance. The federal government offers coverage but many of those eligible never apply.

Further, although it is required by most lenders in flood-prone areas, mandated coverage is often limited to $250,000 -- which is the federal policies' limit for a residence -- or to 80 percent of the replacement cost of the home, whichever is smaller.

Thus, many of the families who have coverage will find themselves responsible for 20 percent of the cost -- $30,000 on a $150,000 home -- if the house is a total loss and they want to rebuild.

And many of the houses will be total losses. Now immersed in what amounts to sewer water up to the roof, many houses may remain under water for weeks or even months. Insulation, wiring, ductwork and other systems will likely be ruined, said William Coulbourne, a structural engineer with URS Corp. in Gaithersburg.

While high-rises could be stripped down to the concrete, power-washed and then refitted, most houses would be much harder to clean up even if they remained structurally sound.

Even once-routine things such as personal and business records will provide months of headaches.

Computer systems will help some. Many institutions, such as banks and insurers, in the hurricane area were able to transmit records to safe backup facilities where they will remain accessible over the Internet.

Individuals and small businesses, too, could do the same, but experience in Florida and elsewhere suggests that many don't.

Many families and businesses "are going to be in a world of hurt" trying to reconstruct their financial lives, said Skip Honigstein of the Orlando chapter of SCORE -- formerly the Service Corps of Retired Executives -- which advises small businesses.

In a disaster such as Katrina, "some stuff is just going to be gone forever, and I don't know how people are going to reconstruct it," said Honigstein, who counseled business owners in the Orlando area after last year's hurricanes there.

However, he said, banks and accounting firms and government agencies such as the IRS, assuming they weren't washed away, too, can help people piece things together. Taxpayers can get a copy of an earlier year's return from the IRS; banks have lists of checks written; credit card companies can get you your payment history.

"A lot of detective work" is involved, Honigstein said, but families and businesses have little choice but to do it.