Missing cost basis on 1099-DAs leaves crypto filers scrambling

Brokers were required to report gross proceeds from certain digital-asset sales on Form 1099-DA for the 2025 tax year. An August survey of 1,000 U.S. crypto investors by Awaken Tax found 21% were still waiting for information from an exchange and about 20% said their 1099-DAs were incomplete or potentially inaccurate.

For 2025, brokers generally reported only proceeds-the sale price of an asset-but not the cost basis taxpayers paid to acquire it. Taxpayers who filed extensions have until Oct. 15 to submit returns. Where cost basis is missing, filers must provide purchase dates, amounts paid and fees to calculate gains or losses.

Tax professionals report frequent mismatches between exchange statements and clients’ transaction records. Sharon Yip, founder of Crypto Tax Advisors, reported cases where 1099-DAs omitted trades and used inconsistent formats. One client had more than $300,000 in stablecoin trades on an exchange while the exchange’s 1099-DA showed under $100,000 in stablecoin proceeds.

Chris Herbst, managing director at CountDeFi tax reporting, warned that reporting proceeds without basis can greatly overstate taxable gains for active traders, because each sale may be counted at full value with no cost deducted. He noted that missing acquisition information can affect calculations across years and platforms since basis follows the asset as it moves.

Delays in issuing forms added to problems. Andrew Duca, founder of Awaken Tax, reported some exchanges issued 1099-DAs late in the filing season, citing examples of forms sent two weeks before the April 15 deadline and at least one form showing no transaction data. He advised filers to verify any form numbers against their own records rather than copying them onto a return.

Software and format limitations have increased manual work. Andrew Gordon, executive director of Digital Asset Tax Action, reported that most crypto tax tools could not import 1099-DA data automatically for 2025 because brokers did not provide machine-readable files. That forces many users, especially active traders, to enter hundreds of individual transactions by hand. Gordon recommended brokers provide machine-readable files and retain full transaction histories with acquisition dates, fees and transfer records.

The IRS reminds taxpayers they must report digital-asset income and gains or losses whether or not they receive a 1099-DA. Reconstructing basis can require compiling records across multiple exchanges, wallets and years, including deposits, withdrawals and transaction identifiers.

Rules change again for 2026: brokers will generally be required to report cost basis for covered digital assets, which should provide more detail to taxpayers. Transfers into a broker from another wallet or exchange may still fall outside reporting requirements. Tax professionals recommend keeping complete transaction histories and checking any 1099-DA against those records before filing.