Cryptocurrency startup Coinbase will provide data on some of its customers to U.S. tax authorities in the coming weeks, the company said Friday.

In an email sent to around 13,000 customers, Coinbase confirmed on Feb. 23 that it will share “only certain limited categories of information” with the Internal Revenue Service (IRS), though it did not disclose the exact details of the information to be sent. Coinbase said in the notice that it plans to provide the data to the IRS within the next 21 days.

The startup advises:

“If you have concerns about this, we encourage you to seek legal advice from an attorney promptly.”

The move comes as a result of a lengthy legal battle between the IRS and Coinbase, which began in 2016 when the tax agency initially sought data on 500,000 Coinbase users.

As reported by CoinDesk, an order from the United States District Court for the Northern District of California in November stipulated that Coinbase must hand over information of more than 13,000 users that had seen over $20,000 trading volume from 2013 to 2015. In the email message, Coinbase claims the reduced number of users affected as a “partial, but still significant, victory.”

According to social media posts, some notable figures in the cryptocurrency industry such as the bitcoin advocate and author Andreas Antonopoulos are included in the data order.

Disclosure: CoinDesk is a subsidiary of Digital Currency Group, which has an ownership stake in Coinbase.

U.S. tax form image via Shutterstock