If you needed to stretch your income to qualify for a mortgage to buy the house you like, would you consider telling a little white lie -- fibbing to your lender?

What if your loan officer thought up some creative ways for you to get into a house you couldn't otherwise qualify to buy, such as cooking up some fake W-2s, credit scores or banking and tax documents?

What would you do? Whatever your answer, the sobering fact is that thousands of people across the country -- home buyers and loan industry personnel -- no longer are playing the mortgage game straight.

Think of it as the little-publicized, seamy underside of the billowing national housing boom: widespread and growing fraud in home loan applications, where sticker-shocked buyers lie about their incomes and assets, and where mortgage brokers create what the FBI calls "air loans" -- fictitious borrowers, houses, addresses, credit reports, bank statements and income verifications.

It is a multibillion-dollar problem, largely unseen by most consumers and loan officers, who wouldn't think of taking part. But a new national report confirms the mortgage industry's fears: Fraud appears to be growing faster now than ever. The FBI received more than double the number of mortgage-related "suspicious activity reports" from 2003 to 2004, and the problem is spreading from the biggest cities out into smaller metropolitan areas such as Tulsa and Scranton, Pa.

The top cities for mortgage fraud last year, according to a new report by the Reston-based Mortgage Asset Research Institute, were Atlanta, Dallas, Denver, Orlando, Charlotte, Memphis, Scranton, Columbus, Houston, Salt Lake City and Louisville. Those cities all have excessively high rates of early defaults on home mortgages closed in 2004, a key indicator of fraud. Though most cases of fraud involve multiple misrepresentations, the institute's study found that fibs and falsehoods on applications by individual borrowers constitute the most common problems (56 percent of all cases), followed by bogus or incorrect tax and financial documents (33 percent), fake employment verifications (12 percent) and fabricated or intentionally inflated appraisals (10 percent).

The research institute report, based on pooled industry fraud data as well as FBI statistics, did not propose ways to cut down on fraud, but instead focused on the types of fraud being perpetrated around the country. Here are some of the patterns investigators found:

* Problems with "stated income" transactions. Known in the industry as "liar loans" or NINAs (no income, no asset verification), these programs were originally designed for highly creditworthy professionals and owners of small businesses who prefer not to show all their documentation on income, investments and other financial assets. Stated income means you state your income and estimate your assets, not prove them with documentation. Typically, stated income loans also carry a slightly higher interest rate or fees to compensate for the perceived higher risk.

But during the housing boom, such mortgages routinely have been extended to applicants with shaky credit profiles and insufficient incomes to qualify for their home purchases. In one case highlighted in the report, a Florida mortgage broker worked hand in hand with a borrower, changing the applicant's supposed income as he shopped for loans from different lenders. When challenged, the broker said: "I thought that with stated income loans you could claim an income as high as necessary" to obtain the loan needed.

* Property flipping fraud networks. If you can assemble a team of dishonest appraisers, title agents, real estate agents and investors, you can fool lenders by flipping properties at hoked-up prices and loan amounts. Federal investigators in Ohio recently broke up a ring of realty and title industry scam artists. They would buy houses, then flip them to new buyers using fabricated appraisals that effectively doubled the properties' values within a few weeks. Lenders who extended mortgages based on the excessive valuations were defrauded.

* Employment or income disinformation. If a buyer's income doesn't make the grade, sometimes unscrupulous loan officers will help them fake it. In a small Michigan town, fraud investigators tracked seven mortgages to a single office where the broker "showed the borrowers employed at a company owned by the broker. Five of the loans contained [accountant] verification forms that were forged. The [accountant's] listed address was the same as that of the broker-owned 'employer.' "

Working with the Mortgage Asset Research Institute and the FBI's financial crimes investigation teams, the home loan industry is mounting an effort to spot the indicators of fraud before mortgages are closed or go into default.

For its part, the FBI is putting out the word: If you attempt to defraud or lie to your lender and you get caught, you are likely not only to pay back any money you received illegally, but also to spend time in the slammer to think about it.

Kenneth R. Harney's e-mail address is KenHarney@earthlink.net.