20th of last month or 2 1. According to the information of official website of the Postal Savings Bank, the due repayment date of the Postal Savings Credit Card is the 20th day after the billing date, so if the repayment date is 10, the billing date is between 20 days; If it is 3 1 day in the last month, the bookkeeping date is 2 1 day; If last month was 30 days, the accounting date was 20 days.