The answer is not just to repay the principal. When a credit card is overdue, in addition to principal repayment, you also need to pay overdue interest, late payment fees and other fees. The following are detailed instructions:

1. Overdue interest: Late repayment will result in overdue interest on the credit card bill. Overdue interest is calculated based on the number of days overdue and the credit card's overdue interest rate, which is usually higher.

2. Late payment fees: Late payment fees are additional fees incurred due to overdue repayment. Each bank has different late payment fee standards, which are generally calculated based on the proportion of the overdue amount.

3. Overdue records: Overdue repayments will have a negative impact on personal credit records and may lead to a decline in credit scores. After your credit score drops, it may affect future loans, credit card applications, etc.

To sum up, if a credit card is overdue, you cannot just repay the principal. In addition to the principal, overdue interest and late fees must be paid, and overdue records will also have a negative impact on personal credit. Therefore, in the case of an overdue credit card, it is recommended to pay it off in full as soon as possible to avoid incurring more fees and maintain a good credit history.

Supplementary information:

Credit card consumption is based on the contractual relationship between the bank and the cardholder, and breach of contract will have an impact on the cardholder's credit. When the cardholder fails to repay the loan overdue, the bank has the right to charge overdue interest and late payment fees from the cardholder. According to Chinese law, banks can take reasonable measures to pursue the repayment of overdue amounts and reserve the right of legal recourse. Therefore, cardholders should try their best to abide by the credit card repayment deadline to avoid the adverse consequences of late repayment.