Credit card accounts are settlement accounts, only current accounts. According to the regulations, a fixed account cannot be used as a settlement account. At the same time, the general bank's credit card (which can be overdrawn) does not calculate interest, and only debit cards or savings cards calculate interest at the current interest rate. If you want to have a convenient settlement function and a relatively high interest rate, you can do this: in addition to credit cards, apply for a seven-day notice deposit from the same bank. At the same time, establish a transfer relationship between the two accounts (this usually requires you to transfer money at any time, either through the counter or through online banking with the permission of the bank). Temporarily unused funds can be transferred to a notice deposit to enjoy a higher interest rate, notify the bank seven days before use, and then transfer the funds from the notice deposit to a credit card.