To apply for a credit card, you usually need to provide proof of the source of funds and proof of repayment ability, and proof of work is one of the common ways. Specific requirements may vary by bank and country, but the following are some common supporting materials related to credit card application:

1. Work certificate: including the work certificate letter issued by the employer to prove your employment status, position and income.

2. Payroll: Provide payrolls for recent months as proof of income, showing your salary, allowances and other sources of income.

3. Bank statement: Provide bank statements in recent months to prove your income and capital flow.

4. Tax documents: such as personal income tax return or tax return, to prove your income level.

5. Other proof of income: If there are other stable sources of income, such as rent, dividends or return on investment, relevant proof documents can be provided.