Many people think of a second mortgage as a fixed interest, lump sum loan. However, that is only one form of a second mortgage. A second mortgage is actually ANY secondary lien on your home--secured loan with your home pledged as collateral. Second mortgages are typically categorized as fixed mortgage rate home equity installment loans (HELs), also known as home equity loans, and home equity lines of credit (HELOCs) which are adjustable rate mortgages.

The Federal Reserve states that the home equity line of credit annual percentage rate (APR) is a variable rate loan based solely on a publicly available index (such as the prime rate published in the Wall Street Journal or a U.S. Treasury bill rate). The APR does not include points or other finance charges. The monthly payment amount will adjust as your loan balance and interest rate changes. Loan terms can be anywhere from 15 to 30 years.

HELOCs have a draw period, typically occurring in the first 10-15 years, with the remaining term on the loan referred to as the repayment period. During the draw period, you can draw out money on a revolving basis similar to a credit card without applying for a new loan, as long as the amount does not exceed the total amount of the original HELOC. During the repayment period you may be allowed to renew the credit line. If your plan does not allow renewals, you will not be able to borrow additional money once the draw period ends. Interest is paid only on the amount of equity you use.

A Home Equity Installment Loan (HEL) is a fixed mortgage rate loan, which means the annual percentage rate (APR) and monthly payment will stay the same for the life of your loan. The APR for a HEL takes into account the interest rate charged plus points and other finance charges. Loan terms can be anywhere from 5 to 30 years, but are typically 15 to 20 years. Unlike a HELOC, you get a lump sum for which you immediately start paying principal and interest. If you decide later that you need additional funds, mortgage refinancing or getting an additional loan with additional closing costs are your only options.

Which type of loan you choose depends on your financial needs. A HELOC may be best if you have a recurring need for money (e.g., home improvements or a home repair project that has anticipated additional expenses). The security of a fixed-rate 2nd mortgage will probably provide much-needed relief for a large one-time expense (e.g., debt consolidation).