The composition ratio of Bank of Communications’ credit card income is:

1. Annual fee income: Credit card holders usually need to pay a certain annual fee to use credit card services, accounting for 40% of their income.

2. Interest income: When a credit card holder fails to repay on time, the bank will calculate interest based on the remaining outstanding amount. These interests are one of the bank's income, accounting for 30% of the income.

3. Fee income: During the use of credit cards, fees such as cash withdrawal fees, overdraft fees, foreign currency transaction fees, etc. may be involved, accounting for 20% of the income.

4. Merchant fee income: When merchants use Bank of Communications credit cards, they need to pay a certain proportion of handling fees to the bank, accounting for 10% of the income. Bank of Communications is a large commercial bank in China. Founded in 1908 and headquartered in Shanghai, China, Bank of Communications is one of the five largest state-owned commercial banks in China. It has an extensive business network and customer base nationwide and overseas.