Proving to the IRS I bought monero years ago

self.Monero13d ago
I have been holding monero for a while. Nothing significant but enough for a down payment on a car. I haven’t sold anything yet as I’m trying to understand the tax implications and whether or not it’s worth it. Technically, I’m subject to 0% tax as my capital gains are below $41,675 and it is a long term position (as opposed to short term) My question is, how do I prove what my capital gains are and that I’ve held it for longer than a year to the IRS? I received the XMR as payment for helping a friend with a game he was developing. I don’t have receipts or anything. Do I have to suck it up and pay the full tax % and mark it as a short term gain?