But compliance with this requirement is virtually nonexistent, at least if you go by numbers reported by the IRS. The agency began going after Coinbase, the largest bitcoin exchange operating in the States, in November 2016, requesting that the San Francisco-based company turn over data and complete transactions on every one of its more than 14 million accounts from 2013 to 2015.

But in court papers filed by the IRS this month — after Coinbase refused to honor the request, complaining that it was “overly broad” — the tax-collecting agency reported that only “802 individuals reported a transaction on Form 8949 using a description likely related to bitcoin” for 2015, the most recently concluded tax year. And this is apparently no fluke, with only 807 of the Form 8949s filed for 2013 and 893 for 2014.

This low level of reporting occurred during the same period (2013-2015) that the value of the currency (in dollars) went on a bumpy ride, skyrocketing from less than $20 to more than $1,100, presumably generating significant capital gains for many investors. “In my view, 800 reports per year of profits and losses in virtual currency transactions is ridiculously low,” says Martin Mushkin, an attorney specializing in bitcoin law.

“The given publicity to this proceeding now and the forthcoming enforcement actions would result in a substantial amount of tax collections,” he adds. “The anonymity of bitcoin should not be allowed to foster tax evasion.” Coinbase, for its part, blames the IRS itself for this underreporting, and its chief executive has called for a creation of a Form 1099-B to be issued to each of its clients participating in a potentially taxable transaction — a proposal that the IRS has called low priority because of cuts to its budget.

“We’re very serious about complying with the laws and we actually support the idea that people who ought to pay their taxes do so,” says Michael Lempres, Coinbase chief legal and risk officer. “But the demand for three years’ worth of transactions conflicts with privacy interests.” Mushkin and others familiar with the case say they expect Coinbase to cut a deal with the IRS. “I suspect that, as we speak, Coinbase is preparing an answer to the anticipated Order to Show Cause and negotiating the terms of the summons,” he says. “The papers show the parties have been talking, and Coinbase will try to cut this down.”

Coinbase is already registered with FinCEN, the Treasury’s Financial Crimes Enforcement Center, obliging the exchange to report transactions in excess of $10,000 per day and suspected transactions to be structured to avoid the $10,000 reporting threshold (such as multiple $9,750 transactions). The Coinbase response, Mushkin predicts, “will be to initially limit the subpoena to FinCEN reporting accounts and smaller accounts with large turnover volumes.”