The result, says Kathleen Day, a spokeswoman for the Center for Responsible Lending, an advocacy organization in Washington, D.C., would be less opportunity for homeowners to refinance.

"They may be stuck in a high-cost mortgage, even (though) the rates are down because the law says they're a risk, even though they're not," she says.

States that have large numbers or substantial percentages of equity-poor homeowners include: Arizona, California, Colorado, Florida, Georgia, Idaho, Illinois, Michigan, Mississippi, Nevada, North Carolina, Ohio, Texas and Utah. That's according to an analysis of CoreLogic data published in a white paper from the Coalition for Sensible Housing Policy, a group of real estate trade associations, consumer organizations and civil rights groups lobbying for a less strict QRM definition.

QRM alternatives

Equity-poor homeowners who need to refinance might want to act before the credit risk retention rule becomes effective, says Ken Dickson, senior vice president of Johnson Bank in Madison, Wis.

"If you're a homeowner today and need to refinance," he says, "the time to do it is now."

Then again, Dickson says, the QRM rule hasn't yet been finalized, which suggests the rush might turn out to be unnecessary.

"'It's not yet finalized' is probably the most important thing I can tell you," Dickson says.

Homeowners also may have other options to refinance, even if the rule takes effect as proposed.