FORT LAUDERDALE, Fla. — Be on guard against those low, low mortgage rates. You may end up spending more by refinancing than if you had stuck with your current mortgage, even if your new interest rate would be under 3 or 4 percent, financial planners warn.

Here are three warning signs for not refinancing your home at a lower rate, they say.

• You're one of the many homeowners who owe more than what the home is worth. Lenders may ask you to pay a higher interest rate, perhaps a quarter- or half-percent more than the average national home-loan interest rate, mortgage brokers say. Even worse, a prospective lender may ask you to pay property mortgage insurance, which will add thousands of dollars to the cost of your loan, said Deerfield Beach, Fla., financial planner Blair Shein.

• There's a chance you might move to take a new job. If you don't stay in your home at least two years you may lose money on refinancing, said financial planner Matt Saneholtz, president of the Financial Planning Association of Greater Fort Lauderdale.

That's because you won't have time to recoup the closing costs, he said.

• You will end up paying more. If you have less than five years to pay, you will generally pay more if you take out a longer loan, even if it offers a much lower interest rate, Shein said.

That's because the longer loan length means more interest costs, although your monthly payment will be smaller, he said.

You only come out ahead if you continue making your existing loan's bigger payments on the new loan. That will ensure you will pay less interest — and pay off the loan even quicker, Shein said. "But the reality is that most people don't do that," Shein said.

Homeowners should examine all the costs before signing up for a new loan.

"Do the math," Saneholtz said.

And beware of the hidden closing costs: You may not have to pay any when you sign for the mortgage, but those costs will be added to your new loan — often involving thousands of dollars, Saneholtz said.