If the billing date of your credit card is the 7th of each month (then your due repayment date is the 26th of that month), and after swiping the card on April 2nd, your consumption will be charged to the bill on the 7th, then your due repayment date is April 26th. So the interest-free period of your CITIC Bank credit card is: (April 7-April 2)+(April 26-April 7) =24 days.

If you spend money by credit card on April 8th, then this charge will be charged to your bill on May 7th, and your final repayment date is May 26th. Calculated, the interest-free period of your CITIC Bank credit card is: (May 7th-April 8th)+(May 26th-May 7th) =50 days.