There is no single-month limit, but you cannot have that much credit limit. Generally speaking, if you spend 20,000 for 4 days in a row, unless you are spending at POS in different malls, the Bank of Communications' Credit Information Department will call you to verify the situation. If you do it online, it will be more troublesome, and you will be suspected of cashing out. It's going to be troublesome if you get caught, so, my friend, it's better to take it easy