The low "teaser" mortgage rates are back. But should home buyers take advantage of them?

At the height of the real estate boom, builders peddled adjustable-rate mortgages with low teaser rates as a way to reel in potential buyers struggling to afford a home.

The problem: Scores of these loans ended in foreclosure when their rates eventually increased and borrowers couldn't afford the higher monthly payments, helping lead to the economic meltdown.

In the past year, there has been little marketing of such variable rate loan products, in great part because of the stigma attached to them and because fixed-rate, 30-year loans remain so enticing, near historic lows of around 5 percent.

In recent weeks, however, the low introductory mortgage rates are back, coupled with tax credits and other incentives. But the loans being peddled aren't technically "adjustable." They are 2-1 "buydowns."

What's the difference? It's subtle, but borrowers still need to pay attention so they avoid some of the pitfalls of adjustables.

A 2-1 buydown is a 30-year loan that has a super-low rate for the first year, a slightly higher rate in the second year, and then a fixed rate for each of the 28 years thereafter.

Holmes Homes, for example, has advertised a 2-1 buydown on a 5 percent mortgage. The buyer pays 3 percent rate in the first year, 4 percent in the second year and 5 percent every year thereafter.

Buydowns also come in the one-year variety. The Mill Creek Terrace condo development last week was offering qualified buyers a 4.625 percent 30-year loan with a 3.625 percent rate for the first year.

Buydowns obviously can be a great deal for buyers -- you get the security of a low, fixed-rate loan at or near market rates with the bonus of lower payments for the introductory period. But consumers need to make sure they budget for the increase in the monthly payment that will inevitably come along.

"Make sure you know what your payment is going to be after the buydown period ends and that you plan for it," said Gary Nielsen, president of the Utah Mortgage Lenders Association.

The increase in the payments can be substantial. On a $250,000 loan at 3 percent, the principal and interest payments are $1,054 per month. At 5 percent, that jumps to $1,342.

Ross Holliday, a principal of Holmes Homes, said buydowns often appeal to young couples stretching to buy their first home. Many count on the expectation that during the buydown period, they'll get a raise or two.

But in this economy, can anyone really count on a raise? Scores of workers instead are seeing their hours, pay and commissions cut.

The good news is that, unlike in years past, lenders are approving borrowers based on their ability to make the highest of payments on the loan.

In the years leading up to the bursting of the real estate bubble, lenders approved borrowers based on their ability to handle payments only at the lowest rates. As a result, borrowers who trusted lenders to tell them if they could afford to buy a home were especially ill-equipped to handle the higher monthly payments when their loan rates adjusted upward.

Holliday points out that the 2-1 buydown is just one option for buyers. Even though the introductory rates are enticing, he said many buyers still opt for fixed monthly payments for the entire loan period. "There is no one thing that works for everybody."

Lesley Mitchell writes One Cheap Chick in daily blog form at blogs.sltrib.com/cheap.