Buying a house with a loan, that is, a bank loan to buy a house for you, you need to repay the principal and interest of the bank loan. When you sell a house, you have to pay the principal and interest of the bank first, and the rest is yours. Of course, this remainder can be an integer, 0 or negative number. You have paid back the principal and interest for two years to the bank, and then deduct it when you sell the house.