1. No, you don't make up your own form but you do provide the proof.
- The 1099-DA is new for 2025 and the way basis is calculated was changed Jan 1, 2025 to be accounted for by wallet or account only. Prior to that date, the IRS did require that you keep a spreadsheet of your investments with your date purchased, sold, basis, gain, loss and any other information to do your taxes.
- Starting in 2026, the 1099-DA will contain basis for you. Although, it is still a good idea to keep track of your investments due to odd things that can happen. You do need to determine your basis and have proof. Otherwise, the IRS deems your basis to be zero.
- Let's work on the basis you need for this year.
- If a transaction says covered - the issuer does know the basis and it may be reported on your form.
- Noncovered -you are responsible for the basis and can determine it by: reviewing transactions, using a blockchain explorer to trace wallet address back to date of acquisition and crypto tax software can help match transfers.
- create a log to use with your return and either upload or mail to the IRS. Again, basis of zero for things not found.
2. It depends: If both of these are true, you do not need to mail the form along with your log:
- Check your form 8949 for exception 2 or code M if you summarized transactions on your return rather than listing all of them
- you uploaded a .pdf of your transaction log to attach to your return.
Otherwise, you need to mail a copy of your 1099-DA and supporting paperwork (your log) with the form 8453 within 3 days of your return being accepted.
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