Can I also deduct credit card fees?

Yes, that is possible. However, only if you can prove that you use the credit card almost exclusively for business trips. Otherwise, you should split the costs of your credit card into a private and business part.

Determine the business usage percentage. The cost portion attributable to business use can be deducted as business expenses.

There is no specific proof required for these costs. One option would be to include copies of credit card statements for three consecutive months of the tax year. Clearly indicate which portion of the credit card transactions was business related. You can then claim this percentage of the credit card fees in your tax return.