Outstanding principal and interest of non-performing loans refers to the borrower's repayment of overdue principal and interest. Non-performing loans refer to loans that borrowers fail to perform on time, are overdue or are unable to repay. When borrowers have bad loans, banks or financial institutions usually take various measures to recover the arrears. Repaying the outstanding principal and interest is one of the ways, that is, the borrower pays off the non-performing loans by paying the overdue principal and interest in one lump sum or in installments.