The billing date for China Merchants Credit Card is the 21st, so it is better to swipe the card on the 22nd. According to relevant query information, the billing date is the 21st. Consumption on the 22nd of each month will have the longest interest-free period, while consumption on the 20th will have the shortest interest-free period. All purchases made before the 21st must be repaid before the repayment date next month, otherwise overdraft interest will accrue overdue interest.