One in four homeowners with a mortgage is now considered "equity rich," meaning that their outstanding mortgage balance is worth less than 50 percent of their home value, according to Attom Data Solutions. TransUnion expects 1.6 million home equity line-of-credit originations this year, double the number seen in 2013.

As house prices continue to rise, home equity is becoming a more attractive — and more accessible — source of cash for millions of Americans.

"Whether you stuck it out through the crisis or you bought in the last five years, many homeowners are sitting pretty when it comes to home equity," said Daren Blomquist, senior vice president of communications at Attom Data Solutions. "It's a good time to leverage that."

Borrowing against home equity can be a convenient way to access cash, but it also carries risk, as millions of Americans learned in the housing crisis of 2008. If you're considering it, here's what you need to know.

1. It's getting (slightly) easier to qualify. Since clamping down on credit after the housing bust, lenders are starting to loosen up. More than 10 percent of large banks eased their credit standards somewhat for HELOCs in the first quarter. Still, you'll need to prove you've got the credit and income to pay off the loan.

Lenders typically want borrowers with a credit score of at least 700 and whose total debt amounts to 43 percent or less of total income. The total HELOC and your mortgage balance usually can't amount to more than 80 percent of your home's value, although some banks are letting consumers borrow 85 percent or more.

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2. The tax rules have changed. Under the new tax law, the home equity interest is only tax-deductible if you're using the money for home renovations on the property tied to the loan. The total amount of home equity debt (including your mortgage) that qualifies for the deduction can't total more than $750,000.

It may still make sense for you to use a HELOC for other purposes, such as debt consolidation or college tuition, but there's no longer a tax benefit to doing so.

3. You'll need to shop around. Get a quote from your current lender, as well as from at least two others, including a credit union and an online bank. Use those quotes to negotiate to make sure that you're getting the best deal. "You can find fairly wide variances in price, interest rates, accessibility and terms from place to place across town," said Keith Gumbinger, vice president at mortgage site HSH.com.

The typical HELOC has a 10-year draw period in which you can take out money as you need it, paying interest only on the money you use. At the end of the draw period, you'll have a 10-year repayment period on the outstanding principle. Since more HELOCs are variable-rate loans, you'll want to know the current interest rate as well as the lifetime cap — the maximum possible rate you'll pay if interest rates go up.