Credit card installment refund reduces the principal, which means that after the user chooses a credit card to purchase goods in installments, there will be a refund, and the bank will directly deduct the refund amount from the user's installment principal. When users choose to use credit cards to purchase goods in installments, the bank will allocate the purchase amount to several installments according to the user's choice, and each repayment includes principal and interest. If the goods purchased by the user are refunded, the bank will directly refund the installment principal of the user.