Supplementary credit card refers to the supplementary credit card that credit card holders handle for their immediate family members, such as parents, spouses and children. The main credit card and the subsidiary credit card share the credit limit of the main credit card. The supplementary credit card has the same function as the main credit card, and can be used for credit card payment, cash installment application and overdraft limit withdrawal. Generally, domestic applicants must be 65,438+04 years old and overseas applicants must be 65,438+08 years old. Subsidiary credit card.