Yessss you need to keep a copy of every business related bank statement and credit card statement. Yessss you need to keep a copy of every receipt for every purchase and a copy of every invoice for every sale. Whether you keep it in a file in the filing cabinet or in a file in the cloud it does not matter. It has to be easily retrievable for up to 6 years in case of an audit. Small, self-employed business owners are more likely to be audited then large corporations.