Many people holding bitcoin have seen massive gains, some becoming overnight millionaires after the currency soared more than 1,000% in value over the last 12 months.

Now comes the less fun part: Paying taxes.

One office assistant’s struggle was shared on Reddit on Thursday, when he discovered he owed $50,000 to the Internal Revenue Service in taxes on cryptocurrency exchanges. The user, who makes about $47,000 per year at his job, said he bought eight bitcoins in 2017 for $7,200 and raked in a profit when bitcoin’s value soared in late 2017.

After selling about $120,000 of coins, he found he now owes $50,000 in taxes — but only has $30,000 left in crypto. He said he only has $5,000 in savings left. He either spent his windfall or invested in other coins, or both. “I feel like I might have accidentally ruined my life because I didn’t know about the taxes,” he wrote.

It’s likely he owes some taxes on these exchanges, though the exact amount can likely be shaved down by a tax professional, a spokeswoman from personal finance website ValuePenguin said.

In fact, anybody involved in cryptocurrency transactions should be paying taxes on them, said Kirk Phillips, a tax professional who specializes in cryptocurrencies and goes by the moniker “The Bitcoin CPA,” whether they have sold hundreds of thousands of dollars’ worth of coins or a made a single $2 purchase.

Because bitcoin BTC, -0.95% and other cryptocurrencies are seen as property by the U.S. government, capital-gains taxes apply to every transaction made. “It can be very tedious,” Phillips said. “I call it the coffee problem: Even if you were just buying a cup of coffee in bitcoin you would have to report every sale of bitcoin.”

Each sale or purchase technically constitutes two transactions: (1) selling property (bitcoin) and (2) using the proceeds of that bitcoin sale to buy a product. So the person who bought a $1 million home using cryptocurrency Ethereum, for example, would have to pay capital-gains tax on the transaction as well as real-estate taxes.

How, exactly, to pay taxes on bitcoin is a complex issue: The Internal Revenue Service has commented on it only once, in 2014, and since then the crypto world has changed immensely.

The American Institute of Certified Public Accountants is sending the IRS a letter requesting more clarity on cryptocurrencies and taxes, but Phillips said it is likely the government won’t comment, if at all, until closer to this year’s tax filing deadline. Because of this, he suggests people with large bitcoin holdings or many transactions to report wait before filing, in case the rules change.

The last time the IRS released guidelines on cryptocurrencies was just days before the individual filing deadline in April 2014. To be safe, Phillips suggested people work with an accountant, in particular one who specializes in bitcoin, especially if they have large holdings. “The more you have at stake, the more important it is to get professional advice,” he said.

For those who want to file taxes themselves, selling bitcoin is treated the same as selling property or any other capital asset. People must report each transaction in terms of whether it was a loss or a gain, which can be difficult given the volatility of cryptocurrencies.

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Perry Woodin, co-founder of blockchain accounting infrastructure company NODE40 and chief strategy officer of HashChain Technology, said the company allows users to plug their Coinbase accounts into the NODE40 technology to receive an itemized list of past transactions to enter onto IRS Form 8949 and send to the IRS at tax time. Of course, not everyone will be paying taxes on their earnings. People who bought currencies later at higher value might have sustained tax losses.

Similar sites exist for small fees, including cointracking.info and Bitcoin.tax. All of these services are easier to use if you have executed all of your transactions on one platform, said Alexander Kugelman, a tax lawyer based in San Francisco. At his firm, lawyers use historical data to track down the price differences to the day and determine whether each transaction reflected a net loss or a net gain.

Because of the lack of clarity surrounding cryptocurrency and taxes currently, taxpayers should report the transactions to the IRS regardless, preferably with the help of a CPA. “Make a good-faith effort to report it,” Kugelman said. “When filing a tax return with the IRS, less information will lead to more questions. If you provide a statement and explanation of what you’re doing and why, they will be more helpful in the end.”