How do I report my cryptocurrency gains on my taxes?

When I started putting money into crypto a while back, the first thing I did was google how to report it because I didn't want any surprises with the tax authorities. The general rule is that any gains you take out - whether by selling, swapping, or converting to fiat - count as taxable income, so you have to declare it as such in your country. The tricky part is that each country has its own rules: some want you to report all transactions, others only net gains, and some don't even have clear regulations yet. My advice is to ask an accountant or check your country's tax authority website because guessing here is risky and every situation is different.

What a lot of people mess up in crypto tax filings is they only focus on the gains they cash out to euros, but ignore that every transaction between cryptocurrencies - like swapping Bitcoin for Ethereum - also counts as a taxable event, even if you haven't touched fiat money. The tax authority sees it as a capital gain, so you have to record the difference between what you paid and what it was worth at the time of the swap. If you have a lot of transactions, start keeping track now, because doing it all at once later is a nightmare and it also raises more red flags.

Spanish tax authorities want you to report every movement as if it were a sale, even if it's just a swap between cryptos - don't wait until you cash out to euros. What a lot of people don't get is that capital gains are calculated based on the price at the exact moment of the transaction, so if you don't keep a detailed record of dates and values, you're really going to make things difficult for yourself later.

The mess with crypto and tax authorities is that nobody actually warns you properly until you get a notification. The key thing to understand is that in Spain every single transaction is taxable: not just when you convert to euros, but every swap, every trade, every movement. You have to calculate capital gains on each operation (selling price minus buying price at that exact moment), and that's a headache if you don't stay on top of it from day one.

What most people don't do is keep a clean record from day one. Download your exchange transactions, cross-reference them with the historical price data on those exact dates (use CoinGecko or similar, which has free historical data), and keep everything in a spreadsheet. Tax authorities are asking for more and more documentation on this, so if you keep an organized record, when you get audited (or whenever you file) you've got everything right there without having to reconstruct anything. It's tedious at first but it saves you headaches later.

One trick that works: when you do crypto-to-crypto conversions, save screenshots of the transaction with date, time, exact amounts and prices. Exchanges usually have a history you can export, but having it documented on your end never hurts. And before each tax filing, contact a tax advisor who knows about crypto - not all of them do, and it costs way less than what a badly filed return could cost you.

Keep a detailed record of every transaction - date, amount, entry and exit price - because that's what tax authorities are going to ask for when they audit you. The other answers covered it well that each swap counts as a sale, but the point that's missing is that you need to be able to prove the cost basis of every crypto you move, and if you don't have it documented from day one, it's almost impossible to reconstruct later. Use a spreadsheet, a tracking app, or even export your exchange history; anything works as long as it's traceable and shows the capital gains calculation step by step.