A home equity line of credit is a form of revolving credit in which your home serves as collateral. Because a home often is a consumer’s most valuable asset, many homeowners use home equity credit lines only for major items, such as education, home improvements, or medical bills, and choose not to use them for day-to-day expenses.

With a home equity line, you will be approved for a specific amount of credit. Many lenders set the credit limit on a home equity line by taking a percentage (say, 75 percent) of the home’s appraised value and subtracting from that the balance owed on the existing mortgage.

If you decide to apply for a home equity line of credit, look for the plan that best meets your particular needs. Read the credit agreement carefully, and examine the terms and conditions of various plans, including the annual percentage rate (APR) and the costs of establishing the plan. Remember, though, that the APR for a home equity line is based on the interest rate alone and will not reflect closing costs and other fees and charges, so you’ll need to compare these costs, as well as the APRs, among lenders

Home equity lines of credit typically involve variable rather than fixed interest rates. The variable rate must be based on a publicly available index (such as the prime rate published in some major daily newspapers or a U.S. Treasury bill rate). In such cases, the interest rate you pay for the line of credit will change, mirroring changes in the value of the index. Most lenders cite the interest rate you will pay as the value of the index at a particular time, plus a “margin,” such as 2 percentage points