Supplementary cards cannot be applied separately. They are based on credit cards under the master credit card. Supplementary cards can be applied for/kloc-parents, spouses and children over 0/6 years old (immediate family members include: parents, spouses and children). Others can't apply for the supplementary card under your main credit card for the first time.

1. Annual fee: the annual fee of the supplementary card is lower than that of the main card, which is generally half of that of the main card.

2. The main cardholder can apply for multiple supplementary cards and change the supplementary cardholders, but the supplementary cardholders have no right to choose to change the main cardholder. In other words, the supplementary cardholder is passive. Just as your father wants to get a supplementary card for you, he can also choose to get a supplementary card for your mother. But you can't ask the bank to be a secondary card under your aunt's main card.

3. Limit: the overdraft limit of the secondary card cannot exceed that of the primary card.

4. Repayment: There is no need to repay after the secondary card swipes the card, and all overdrafts of the secondary card and the primary card are repaid by the primary card holder.