New documents have emerged in the midst of the closely-watched legal battle between the U.S. Internal Revenue Service (IRS) and digital currency exchange Coinbase, revealing that only a small number of digital currency owners in the United States are reporting their profits or losses in their annual tax returns.

Last week, the tax agency filed an affidavit from IRS agent David Utzke in a San Francisco federal court that disclosed additional details about how IRS is conducting its investigation into possible tax fraud committed by residents in the United States who engaged in business with or through Coinbase.

Utzke said he ran a computer analysis on the IRS’s tax records and found out that less than a thousand people filed a Form 8949 for a “property description likely related to bitcoin.” Under current IRS rules, bitcoin owners are required to declare their profits using the said form.

“…In 2013, 807 individuals reported a transaction on Form 8949 using a property description likely related to bitcoin; in 2014, 893 individuals reported a transaction on Form 8949 using a property description likely related to bitcoin; and in 2015, 802 individuals reported a transaction on Form 8949 using a property description likely related to bitcoin,” Utzke said in his affidavit.