What Documentation Do I Need to Keep?

The IRS needs contemporaneous evidence in the form of a receipt or invoice for all of your business expenses. A bank statement or credit card will not work for the IRS.

It's best practice to scan all of your receipts or invoices into your accounting system and match those receipts with the corresponding transaction. Paper receipts are not necessary to keep, and in fact will fade in a few months. Digital is okay for the IRS.