Credit card sub-cards also belong to credit cards. A supplementary card is a supplementary card, which means that when the applicant of the main credit card applies for a credit card, the credit card applied by his immediate family is a supplementary card. The secondary card and the primary card are different cardholders.

The secondary card has a credit line, and the source of the credit line is the main card. For example, the credit line of the main card is 1 1,000 yuan, and the credit line set by the auxiliary card is 5000 yuan. If the secondary card costs 5000 yuan, then the secondary card has no credit limit, and the credit limit of the main card is only 5000 yuan. It can be said that the secondary card and the main card share a quota, and the quota setting of the secondary card must be smaller than that of the main card.