Pillar guide

What is a 1099-DA mismatch?

The word “mismatch” can describe four different record problems. Identify which one exists before trying to correct anything.

Published July 18, 2026Prepared by Digital Echoes AcademyEducational—not tax advice

Direct answer: A possible 1099-DA mismatch occurs when the form does not align with the broker’s underlying transactions, your original acquisition records, wallet-transfer trail or tax-software output. The mismatch may involve proceeds, basis, transfers or classification. A difference is a reason to review the records—not automatic proof that the form is wrong.

1. Proceeds mismatch

The gross proceeds on the form do not match the transaction-level disposal record you expected. Compare the exact asset, quantity, date, transaction type and USD value. Do not use missing basis to explain a proceeds difference; they are separate questions.

2. Missing or zero basis

The sale is visible, but the original acquisition price is not connected. This often occurs when an asset was bought somewhere else, transferred through self-custody or acquired before the reporting platform had the relevant history. Find the original acquisition, fees and transfer trail.

3. Transfer gap

An outgoing asset on one platform is not matched to the incoming asset on another. Use withdrawal and deposit records plus the public transaction hash. Add the context of whether you controlled both accounts. Never share a seed phrase or private key.

4. Software classification difference

Tax software may disagree with the broker form because an account is missing, imported twice or classified differently. Common examples include own-wallet transfers treated as disposals, bridge transactions left unmatched and older acquisitions omitted.

DifferenceFirst evidenceFirst question
ProceedsBroker disposal exportWhich exact reported transaction differs?
BasisOriginal acquisitionWhere and when was the asset acquired?
TransferSend, receipt and hashCan the same asset be followed?
ClassificationSoftware import logIs a source missing, duplicated or misclassified?

What to do next

  1. Mark the exact disagreement.
  2. Gather the record supporting each side.
  3. Reconstruct transfers before treating deposits as unsupported acquisitions.
  4. Review imports and classifications.
  5. Contact the issuer for a specific form-level discrepancy.
  6. Seek qualified advice when tax treatment remains unresolved.

Start with records, not assumptions

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Sources and limits

See IRS — Understanding Your Form 1099-DA. This guide does not calculate tax or determine whether a form is correct.