How to Fix an Incorrect Form 1099-DA or Missing Crypto Cost Basis

A Form 1099-DA mismatch does not always mean the broker made an error. For 2025 dispositions reported in 2026, brokers generally reported gross proceeds without mandatory cost basis. Missing basis, incorrect proceeds, an unknown transfer, duplicate reporting and a wrong holding period require different responses. This guide focuses on reconciliation, correction requests and the 2025 Form 8949 treatment rather than repeating a general introduction to Form 1099-DA.

Short answer: what should you do when Form 1099-DA looks wrong?

First identify whether the form contains a reportable error or merely omits information the broker was not required to provide. A 2025 Form 1099-DA generally reports gross proceeds from broker digital-asset dispositions. Mandatory basis reporting did not generally apply to those 2025 sales. A blank basis therefore can be expected and is not automatically a defective form.

If the asset, units, sale date, gross proceeds, taxpayer identity or withholding is wrong, contact the issuer and request a corrected Form 1099-DA. The IRS tells recipients to keep the original form and correspondence, not to contact the IRS to correct the broker’s document, and not to wait indefinitely to file.

Diagnose the Form 1099-DA before changing the return

Compare the recipient form with the broker’s year-end statement and raw transaction history. Confirm the legal name, taxpayer identification number, account number, digital-asset name or code, units, acquisition date if shown, disposition date, proceeds, basis, accrued market discount where relevant, gain type, federal withholding and the noncovered indicator.

Then determine which of four problems exists:

1. Correct form, incomplete basis: the broker properly reported proceeds and did not report basis.
2. Incorrect broker data: the broker reported the wrong asset, units, date, proceeds or taxpayer.
3. Correct form, incomplete taxpayer ledger: an owned-wallet transfer hides the original acquisition.
4. Import duplication: the form is correct, but tax software also imported the same sale from API or CSV history.

Changing the tax return is appropriate only after the cause is understood. An unexplained “adjustment” that forces a preferred gain can create a larger mismatch than the original problem.

What Form 1099-DA does not prove

• Gross proceeds do not equal gain.
• A blank basis does not equal zero basis.
• A broker-reported transfer does not establish a taxable change in ownership.
• One broker form does not cover other exchanges or self-custody wallets.
• No form does not mean no reporting obligation.
• A broker’s short/long label does not override the actual acquisition history when it is wrong.

How to reconstruct missing crypto cost basis

Adjusted basis generally starts with what the taxpayer paid for the exact digital-asset units, including applicable acquisition costs, and reflects later adjustments. Digital assets received as taxable compensation or rewards generally begin with basis equal to the amount included in income. Gift, inheritance, business inventory and certain other acquisitions follow different rules.

1. Identify the exact asset units sold and the broker sale transaction ID.
2. Trace any inbound transfer to the sending wallet or exchange account.
3. Continue tracing until the purchase, income receipt, gift or other acquisition is found.
4. Verify beneficial ownership remained with the taxpayer during self-transfers.
5. Apply the taxpayer’s valid lot-identification method and supporting records.
6. Carry the original acquisition date and basis through every owned-wallet transfer.
7. Add or allocate applicable acquisition costs and later basis adjustments.
8. Preserve hashes, timestamps, statements, price evidence and matching notes.

Do not choose HIFO after year-end solely because it produces the smallest gain if the applicable specific-identification requirements were not satisfied. The federal rules moved toward wallet- or account-level basis tracking, and adequate identification remains a documentation question rather than a software preference. The US capital-gains guide covers basis and holding periods in more detail.

Basis for reward income

If 100 tokens were included in ordinary income at a fair market value of $250 when the taxpayer obtained dominion and control, the initial basis generally is $250. A later sale for $300 normally produces $50 of later gain before applicable costs, not a $300 zero-basis gain. Reconcile the original income schedule with the later disposition to avoid double counting.

How to request a corrected Form 1099-DA

The IRS directs recipients to contact the filer identified on the form. Submit a concise, transaction-specific correction request rather than a general statement that “the gain is wrong.” The broker reports form fields, while the taxpayer calculates the final tax result.

Correction request checklist

• Taxpayer name and masked account identifier.
• Tax year and form document or correction number.
• Asset name, exact units and sale transaction ID.
• Field as reported and the requested corrected value.
• Broker statement, trade confirmation or ledger evidence.
• Explanation of a duplicate, cancellation or account-ownership error.
• Request for a corrected recipient statement and IRS filing.

Keep the original form, all messages, ticket numbers and the corrected form. The IRS says not to wait to file solely because a correction is pending. If a correct replacement is not available by the filing deadline, use the current form instructions and documented correct facts, and consider professional advice on the appropriate adjustment or disclosure.

Incorrect taxpayer or identity theft

A Form 1099-DA for an account the taxpayer did not own is not a normal basis-reconciliation problem. Contact the issuer immediately, preserve evidence and follow the IRS identity-theft process if unauthorized activity or identity misuse is suspected. Do not create fictional basis to offset someone else’s proceeds.

Report the reconciled result on 2025 Form 8949

For 2025, Form 8949 introduced separate digital-asset categories. Part I reports short-term transactions and Part II long-term transactions:

Use category H or K when the broker reported the sale but did not report basis. Enter the taxpayer’s correct basis in column (e) under the instructions. Do not move the transaction to I or L merely because basis was missing; those categories are for transactions not reported on a broker form.

If basis was reported to the IRS but is incorrect, the Form 8949 instructions generally require the reported basis in column (e) and a correction through the applicable adjustment code and column (g). If basis was not reported, the instructions generally allow correct basis in column (e) without the same basis correction adjustment. Follow the exact current-year instructions and the Form 8949 guide.

Transaction costs and adjustment code E

The 2025 instructions address digital-asset transaction costs not reflected on Form 1099-DA. They direct taxpayers in applicable cases to report broker proceeds and basis, use adjustment code E and enter the necessary cost adjustment in column (g). Do not reduce broker-reported gross proceeds in a way that breaks reconciliation without following the instructions.

When Form 8949 detail can be summarized

Certain basis-reported transactions without adjustments can qualify for direct Schedule D summary treatment. Other transactions may be aggregated under separate statement rules. A summary does not erase the requirement to maintain and, when required, submit transaction-level detail containing the same information as Form 8949.

Complete 1099-DA reconciliation workflow

1. Inventory every Form 1099-DA by issuer and account.
2. Compare each form’s proceeds with raw broker sales.
3. Match broker sales to the independent all-wallet ledger.
4. Trace transferred-in assets to original basis and date.
5. Classify the proper G/H/I or J/K/L category.
6. Identify genuine broker errors and submit correction requests.
7. Remove duplicate software imports without deleting the economic sale.
8. Apply Form 8949 adjustments under the current instructions.
9. Reconcile Form 8949 category totals to Schedule D.
10. Archive original and corrected forms, source files and workpapers.

The crypto tax records checklist helps document transfers, prices and source provenance. For a field-by-field overview of the new form, use the complete Form 1099-DA guide.

Common Form 1099-DA correction mistakes

• Treating a blank 2025 basis as a broker error.
• Reporting gross proceeds as taxable gain.
• Entering zero basis without tracing transferred assets.
• Moving a reported sale into category I or L because basis is absent.
• Overwriting broker-reported basis without the required adjustment.
• Deleting one of two genuine partial sales as an assumed duplicate.
• Adding an invented purchase to balance the account.
• Waiting past the filing deadline without filing or extending.
• Contacting the IRS instead of the form issuer for a broker correction.
• Failing to retain correspondence and the corrected recipient statement.

Frequently asked questions

Official and primary sources

• IRS: Understanding your Form 1099-DA and correction steps
• IRS: About Form 1099-DA and current revisions
• IRS: 2025 Form 1099-DA
• IRS: 2025 Instructions for Form 1099-DA
• IRS: 2025 Instructions for Form 8949
• IRS: digital asset transaction FAQs
• IRS: digital asset filing and basis overview

Tax status: September 2, 2026. This article addresses 2025 dispositions and the forms used during the 2026 filing season. Use the instructions for the actual transaction year because broker basis reporting expands for certain covered assets after 2025.

Disclaimer: This article is for general informational purposes only and does not constitute tax advice. For individual tax advice, consult a licensed tax professional.