A home equity line of credit is a loan in which the lender agrees to lend a maximum amount within an agreed period (called a term), where the collateral is the borrower's equity in his/her house (akin to a second mortgage). 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.
A HELOC differs from a conventional home equity loan in that the borrower is not advanced the entire sum up front, but uses a line of credit to borrow sums that total no more than the credit limit, similar to a credit card. HELOC funds can be borrowed during the "draw period" (typically 5 to 25 years). Repayment is of the amount drawn plus interest. A HELOC may have a minimum monthly payment requirement (often "interest only"); however, the debtor may make a repayment of any amount so long as it is greater than the minimum payment (but less than the total outstanding). The full principal amount is due at the end of the draw period, either as a lump-sum balloon payment or according to a loan amortization schedule.
Another important difference from a conventional loan is that the interest rate on a HELOC is variable. The interest rate is generally based on an index, such as the prime rate. This means that the interest rate can change over time. Homeowners shopping for a HELOC must be aware that not all lenders calculate the margin the same way. The margin is the difference between the prime rate and the interest rate the borrower will actually pay.