The Coinbase exchange has sent its US customers tax receipts for 2017, causing criticism from its customers for irrational calculations of their capital gains.

Coinbase US customers received 1099-k taxation forms from the cryptocurrency holding. The letters were sent only to those US customers, who made more than 200 trades or whose trading volume exceeded $20,000 in 2017. Coinbase explained the selective nature of e-mails by their intention to remind those customers, who used their accounts for business purposes, to pay taxes.

"We used the best information available for us to determine if your account action qualifies as Business Use, including but not restricted to factors such as completion of a retailer account or allowing merchant tools."

But many users claimed that their trades were counted in error.

Customers also complain in social networks that they were not warned about the upcoming need to fill out this form, and also that the indicators were higher than they expected.

According to US tax legislation, taxpayers should submit detailed information about each of their trading transactions and pay taxes on their capital gains.

In November 2017, Coinbase lost the claim to the Tax Service (IRS), which demanded they provide customers' personal information. The San Francisco court ordered the exchange to hand to the agency the personal data of 14,355 customers who bought, sold, sent or received more than $20,000 between 2013 and 2015.