Conclusion: When repaying a credit card, if you choose the minimum repayment, the interest calculation method is to calculate interest separately for each purchase. Here is an example to help understand: Suppose you spend 100 yuan on December 10, 50 yuan on the 12th, and 5,000 yuan on the 13th. If you only repaid 515 yuan on January 28, this is regarded as the minimum repayment, of which 365 yuan is used to repay part of the consumption (100 50 5000), and the remaining 15 yuan is interest. Starting from the 14th, the remaining 4,635 yuan will start to calculate interest at 0.05% per day. For each new purchase, interest will accrue from the day of purchase.

The minimum repayment policy allows cardholders to repay 10% of the consumption amount plus other fees when they are unable to repay in full, but this will result in the inability to enjoy the interest-free period and the remaining balance will not be repaid. Interest will be accrued on the next month's bill. The calculation formula of the minimum repayment amount includes 10% of the consumption balance, 10% of the cash withdrawal balance, interest balance, installment consumption balance, other payable expenses and the unpaid portion of the minimum payment amount of the previous period, which is listed in detail on the bill.

The above information comes from the Postal Savings Bank of China’s announcement on credit card business charges. Understanding how interest is calculated on minimum payments can help you better manage your credit card bills and interest expenses.