It doesn’t matter. The underpayment of the ICBC credit card will not generate a lot of interest. For example, if the payment is underpaid by 30 yuan, only 30 yuan of interest will be charged. The interest on 30 yuan is 0.5‰ per day, and the daily interest payment is 0.15 yuan cents. The monthly interest is 0.45 yuan, which can be ignored. Because ICBC credit card is one of the few banks that cancels the full amount of penalty interest, that is, when the cardholder cannot repay the full amount at maturity, interest will no longer be charged on the repaid portion. The repayment method is not determined when you apply for the card and can be chosen at any time. For example, if the poster spends 300 yuan with his card and owes 30 yuan, this situation does not matter and will not affect his credit. Even if you spend 100 yuan with your card and owe 30 yuan, it doesn't matter. There will be no bad records.