Jumbo loans are mortgages that are too big to be bought by Freddie Mac and Fannie Mae, which buy most of the home loans made by banks and mortgage companies.

That's what makes jumbo loans more expensive and difficult to get than mortgages that can be bought by the two government-owned companies.

How much more expensive?

About 1.5 percentage points more expensive. That can add almost $1,000 a month to the interest payment on a $750,000 mortgage.

So it's good news that the new economic stimulus plan includes a provision to let Fannie and Freddie resume buying bigger loans, much as they were allowed to do last year.

Until early 2008, Fannie Mae and Freddie Mac weren't allowed to buy loans for more than $417,000.

That forced lots of borrowers in high-cost areas of the country like Los Angeles, where the median home price had soared to more than $593,000 in 2007, into more costly jumbo loans.

When home sales slowed, Congress in February 2008 temporarily raised the limit for loans that conformed to Fannie and Freddie's rules from $417,000 to $729,750 in high-cost areas.

Each city had its own limit based on the area's median home price.

The higher limits weren't permanent, however. On Jan. 1, 2009, the maximum jumbo conforming limit dropped to $625,000.

But home sales are still lackluster, so the American Recovery and Reinvestment Act of 2009, passed this February, kicked the Fannie and Freddie limits back up to a maximum of $729,750 until the end of the year.

About 200 U.S. counties will have higher limits, which aren't expected to go into effect for at least another couple of weeks.

To find the limit in your area, go to the Office of Federal Housing Enterprise Oversight.

If you're thinking about buying a home, find out how to land the best loan.