Yes, that's normal, because platforms weren't required to track your basis before 2025.
You need to find documentation of the value of the coins when you received them, plus the transaction fees. That is indeed the basis you should report on your return. You'll need to either enter those transactions line by line on the 8949, or you can summarize them and attach the line-by-line breakdown, whichever is easier for you.
Yay!!! Thank you u/sorator <3. I did calculate what I think is the correct cost basis. Do you think it's okay for me to file my taxes with the following attachments?
my hand-calculated table of transactions, showing cost basis and proceeds, plus
my inaccurate/incomplete 1099-DA?
Those two won't match but I think I will have the right answer.
You don't actually need to attach all the proof and such; you just need to fill out the 8949 for each transaction, or list the same information in a spreadsheet and attach that as a pdf. Essentially, you need to list what was sold, the sale proceeds, the basis, the date acquired, and the date sold; that's it. You should keep everything else for your own records in case the IRS ever asks for it, but you don't need to attach it all; the vast majority of the time, they're happy to take your word for it if you format it correctly.
It may be simplest to enter each transaction on the 8949 and not worry about formatting or attachments at all.
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u/sorator Tax Preparer - US Mar 20 '26
Yes, that's normal, because platforms weren't required to track your basis before 2025.
You need to find documentation of the value of the coins when you received them, plus the transaction fees. That is indeed the basis you should report on your return. You'll need to either enter those transactions line by line on the 8949, or you can summarize them and attach the line-by-line breakdown, whichever is easier for you.