Up to 2015, I operated a credit card merchant account (First Data) where I would process event ticket sales on behalf of clients, and ACH transfer them their funds. Of the money processed, perhaps 3% is income. I no longer do this model (for many reasons) and use Stripe instead.
Naturally, First data sent me a 1099 saying I made a bunch of money. IRS knows that. I don't report 1099's on my returns directly, because I have an accounting system that includes all of that income.
So clearly, I can explain to a layman why this money is not income, but what is the proper way to respond to this letter and prove it, hopefully avoiding an audit?
Thanks.