Excuse me, I didn't quite understand what you meant. I've accumulated this sum of bitcoin through a variety of sources. I haven't bought a single one. Theoretically, isn't this income something that should be declared? I'm talking about the whole amount of coins.
What I meant is that it's only you who knows where you've got those coins from and whether it's by working for them, or mined, or you've bought them long ago when KYC was not everywhere. And I don't think that anybody would invest too much of resources to find out if your declaration is for real or it's hiding a bit of details here and there.
Hence if you declare them as income then you'll probably pay income tax and if you declare them as capital gains (from 0 since you don't have receipts), then you'll pay capital gains tax.
That's how I see the things.
Thank you for your great explanation, which makes perfect sense. Either I declare the whole amount as income or as capital gains and pay the corresponding tax. In both cases, if I decide to go that way, I'll have to choose which one is more affordable in my case.
So, OP, you're question is basically how to avoid tax and not get in trouble.
You're from Greece, which means the EU, you're also not selling till $50 000 and if we start from the presumption it will be quite a bit of money I would advise you to not try even a p2p deal in cahs in Greece and this is the same for everyone else, not try it in your home nation and not in your hometown.
Get a cheap flight, arrange for a p2p deal in Croatia, Romania, Bulgaria, Hungary, or whatever as close as possible because of costs, and meet there with multiple! again, multiple traders split the sums. Or you can try finding some ATMs that still have limits for like 500E till they require KYC and visit 10 of them a day, sending each transaction from a different address so they don't red flag it.
And, be careful what you do with the cash after!
It doesn't matter how you accumulated it, the tax will be based on what you choose FIFO or weighted average and what proof you have you have bought that amount at x price.
And no, it's still capital tax gains, it will be 15%.
So if you have proof you've bought coins at $1000 and you sell at $50 000 you will pay only for how much you sell 15% of the 49k difference.
Thank you for your detailed response. I appreciate it. Yes, the ideal scenario would be to avoid paying taxes and not get into trouble. Even if I could possibly find someone for a P2P in-person exchange, I'd avoid it. It sounds too risky to exchange a few thousand dollars in person.
The most dominating scenario so far would be to exchange my Bitcoin into a stablecoin when the time comes, withdraw small amounts from exchanges that no one would bother with, and the rest from ATMs, cryptocurrency cards, or abroad when I get the chance.