When the loan to value (LTV) is higher than 80% lenders will generally not be able to do the transaction. In these cases, the borrowers can get private mortgage insurance (PMI) which is a guarantee to the lender that until the borrower reaches a 80% LTV, they are covered from default. To get this protection, borrowers pay a monthly PMI premium. One popular option to get around paying PMI is to take a second mortgage and use it as a down payment on the first.