The bill date is pushed back 25 days to be your repayment due date. Because of the relationship between the big and small months, sometimes the repayment is required on the 3rd and sometimes on the 4th. The longest interest-free period is 56 days, and the shortest is only 25 days. This is determined based on your billing date and the time your card was swiped. Generally speaking, your bill date is the 9th. Your consumption before the 9th of this month will be included in your bill on the 9th of this month. Your consumption after the 9th of this month will be included in your bill on the 9th of the next month. For consumption, the repayment due date is always pushed back 25 days from the bill date. Therefore, to enjoy the longest interest-free period, you must make purchases on the 10th.