You need to get the bank's consent or repayment before you can transfer it to your son's name. During the mortgage period, if the mortgagor transfers the mortgaged property with the consent of the mortgagee, the proceeds from the transfer shall be paid off or deposited with the mortgagee in advance. The part of the transfer price exceeding the amount of creditor's rights belongs to the mortgagor, and the insufficient part is paid off by the debtor. During the mortgage period, the mortgagor shall not transfer the mortgaged property without the consent of the mortgagee, except that the transferee pays off the debts and extinguishes the mortgage on his behalf.