Calculation formula:
Compound interest calculation formula: compound interest = (principal+settlement interest of the previous period) * default interest rate * settlement period.
During the performance of the contract, compound interest shall be calculated at the interest rate agreed in the contract, and after the expiration, compound interest shall be calculated at the penalty interest rate.
Article 20 of the Regulations on the Administration of RMB Interest Rate (Yinfa [1999] No.77) "The interest that cannot be paid on schedule during the loan period shall be compounded quarterly or monthly according to the contract interest rate, and the compound interest shall be calculated at the default interest rate after loans overdue";