@W0405582 Thanks for the question!!
Credit card statement is a good evidence of expenses for business but may not be sufficient. The burden of proof lies on the tax payer claiming the expenses.
Yes, it proves that an expense was incurred, and paid, however it does not prove that the expense was an “ordinary and necessary” business expense. For example, you purchased some items from an office supply store with your credit card. Without the receipt you have no proof that this was a business expense and not, let’s say, school supplies for your children. Another good example is a restaurant charge. In this case, make sure to keep the receipt as well as a note documenting who you took out to eat and the purpose of the meeting. The receipt alone will not prove that the meal had a business purpose, so it is good to keep notes in case of an audit.