Starting with the 2026 tax year, the cost basis of your crypto sold or disposed of will be reported on IRS Form 1099-DA. What happens if the 1099-DA has missing or incorrect cost basis? How should the taxpayer report the correct amount on a tax return? Missing or incorrect cost basis is the most common issue on the new Form 1099-DA. For the 2025 tax year (filed in 2026), brokers often only report the gross proceeds and leave the cost basis blank because they cannot see the original purchase if the asset was transferred from another exchange or a self-custody wallet. A blank or zero cost basis on a 1099-DA does not mean you owe taxes on the entire sale amount. The broker is simply reporting the limited data it has. You are responsible for proving your actual cost basis to the IRS using your complete wallet and exchange history. If the cost basis is missing because the original purchase took place outside of that specific exchange, there is no need to request a corrected Form 1099-DA. The exchange cannot report data it never had. You are allowed to provide the IRS with your own records to fix the issue directly on your tax return. You must correct the missing or inaccurate cost basis when you file your taxes on Form 8949 (Sales and Other Dispositions of Capital Assets). Here is how to handle reporting cost basis on the tax return: 1. Match the Proceeds: Ensure the proceeds (the sale amount) you report in Column D match exactly what the exchange reported to the IRS on the 1099-DA. This prevents the IRS automated matching system from triggering a mismatch notice. 2. Enter Your Actual Cost Basis: Enter the correct cost basis that you calculated (either manually or using crypto tax software) into Column E. 3. Use Adjustment Codes: If the broker reported an explicitly incorrect cost basis to the IRS (rather than just leaving it blank), you must use Column F to enter an adjustment code (such as Code B for a basis adjustment) and Column G to enter the adjustment amount. This ensures your final gain or loss in Column H reflects reality while still showing the IRS you accounted for the numbers on the 1099-DA. Always ensure you have saved documentation, such as trade exports, wallet records, and transaction IDs to prove the cost basis you claim on your return in the event of an audit.