To take on a loan, the buyer must qualify with the lender. If the price of the house exceeds the remainder of the mortgage, the buyer must remit a down payment that is the difference between the sale price and the mortgage. If the difference is substantial, the buyer may need to obtain a second mortgage.7To take on a loan, the buyer must qualify with the lender. If the price of the house exceeds the remainder of the mortgage, the buyer must remit a down payment that is the difference between the sale price and the mortgage. If the difference is substantial, the buyer may need to obtain a second mortgage.8