The U.S. Internal Revenue Service (IRS) is mass-mailing notices to taxpayers with virtual-asset transaction histories, reminding them of their tax filing obligations. According to tax specialists and industry officials, inquiries from taxpayers who say they have received “Letter 6174” have risen noticeably of late, and the volume of mailings itself is expanding.

Clinton Donnelly, CEO of crypto tax specialist firm Cryptotaxaudit, said contacts from clients who recently received IRS Letter 6174 have surged. In a post on X, he said “this is no longer a problem confined to a handful of cases,” noting that dozens of people, including his firm’s clients, have received the notice and reached out with questions. He had earlier flagged that…