See how IRS automated matching can trigger notices when 1099-DA forms lack basis
Highlights
- Form 1099-DA often reports proceeds, but not cost basis, for crypto sales.
- IRS automated matching can flag discrepancies between 1099-DA data and a taxpayer's return.
- Accurate cost basis records and reconciliation can help reduce CP2000 notice risk.
Crypto has entered the information-reporting era, and practitioners have already flagged a gap. For 2025 transactions, brokers report gross proceeds on Form 1099-DA, but they aren’t required to report basis. In fact, the IRS has said most Forms 1099-DA for 2025 transactions will not include basis, leaving taxpayers to calculate it themselves to determine the correct gain or loss.
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What Form 1099-DA reports to the IRS
Why does a 1099-DA mismatch trigger a CP2000 notice instead of an audit?
What causes a 1099-DA cost basis mismatch?
How do you reconcile a 1099-DA with your crypto records?
How to catch 1099-DA mismatches before filing
When does broker basis reporting start for digital assets?
What Form 1099-DA reports to the IRS
The IRS instructions say brokers must report gross proceeds for each 2025 sale, but don’t need to report the cost basis. The IRS receives a copy of every form, and its Automated Underreporter (AUR) function compares third-party information against your return.
Consider an investor who bought a token for $42,000 and sold it for $50,000. The real gain is $8,000. The broker reports $50,000 of proceeds and no basis. If the return omits the sale, or reports figures that don’t tie to the form, the discrepancy can make it appear that as much as the full $50,000 of proceeds is unreported unless the return supplies the basis needed to calculate the actual $8,000 gain.
The challenge with IRS automated matching crypto sales is that the IRS may receive information showing gross proceeds but not the cost basis needed to calculate the taxpayer’s actual gain or loss.
Why does a 1099-DA mismatch trigger a CP2000 notice instead of an audit?
A CP2000 isn’t an audit, nor is it a bill. Instead, it’s an inquiry that proposes changes when information the IRS received from third parties doesn’t match information reported on the taxpayer’s return.
The notice summarizes proposed changes to your tax, generally with interest, and certain penalties may also apply. The IRS says to respond within 30 days of the notice date, or 60 if you live abroad. Paying the proposed amount within 30 days stops additional interest, and possibly additional penalties, from accruing.
If you disagree, you return the response form with a signed statement. If you don’t respond and a balance is proposed, the IRS will issue a statutory notice of deficiency.
Here’s the hard truth about IRS automated matching crypto sales: It’s efficient for the government, but unforgiving for the taxpayer. When broker-reported information doesn’t include basis, the taxpayer’s records may be necessary to establish the correct taxable gain or loss.
What causes a 1099-DA cost basis mismatch?
- Missing basis: For 2025, brokers aren’t required to report basis, so most forms show proceeds alone. Where a broker does report basis voluntarily, it can be incomplete or wrong.
- Noncovered holdings: From 2026, basis reporting is mandatory only for covered assets. Assets acquired before 2026 or transferred into a broker’s custody are noncovered, so the broker isn’t required to report their basis. Long-held, multi-wallet portfolios are the most exposed.
- Missing forms: A client may never receive a 1099-DA, but the duty to report the sale remains.
- Return-side errors: Proceeds entered without following the transaction-cost treatment reflected on Form 1099-DA, omitted sales, or double-counted dispositions. Treating a blank basis field as zero can also overstate gain.
How do you reconcile a 1099-DA with your crypto records?
Practitioners describe this as forensic work, because the form can’t simply be plugged into a return. The sequence is predictable:
- Inventory every wallet, exchange and custodian used during the year.
- Match each 1099-DA line to a disposition in your own ledger.
- Rebuild acquisition lots so each sale carries a defensible basis.
- Report each sale on Form 8949 using the digital asset boxes (H for short-term and K for long-term when basis wasn’t reported to the IRS). Enter proceeds exactly as shown on the 1099-DA in column (d) and your own basis in column (e). If a broker-reported basis is wrong, the form’s instructions have you enter the reported figure in column (e) and correct it with an adjustment.
- Keep the supporting records.
The risk isn’t just on the client. As one digital asset practitioner told Accounting Today, the signing preparer remains responsible for return positions even when numbers come from client-supplied reports or third-party software, so treating that data as a black box is unwise.
Doing this before filing is routine. Doing it afterward, as crypto CP2000 notice reconciliation on a 30-day clock, is far costlier.
How to catch 1099-DA mismatches before filing
Structured extraction of 1099-DA line items is the first line of defense, because it turns a PDF into data you can compare. Diagnostics then flag what becomes a notice:
- 1099-DA proceeds with no matching disposition in the ledger
- Sales with no acquisition lot, a classic sign of a missing transfer
- Proceeds that differ from ledger values beyond a fee tolerance
- Transferred-in or noncovered flags, which signal basis the broker can’t supply
- Forms issued for accounts absent from the books
Because AUR matching happens after filing, a fix at that stage is a response, not a correction.
When does broker basis reporting start for digital assets?
Basis reporting begins for 2026 sales, but only for covered securities, meaning digital assets acquired after 2025 in an account where the broker provided custodial services and held them until sold. Anything acquired earlier, or transferred in, stays noncovered, and basis reporting for it is voluntary. The window narrows rather than closes, and legacy holdings will carry mismatch risk for years.
That makes this season the time to build clean, lot-level records. Your own records will still decide whether the IRS’s number matches reality, and every sale you reconcile now is one less notice to answer later.
Reconciling 1099-DA proceeds and basis in UltraTax CS
UltraTax CS from Thomson Reuters helps you finish the job at the return. Enter each sale’s proceeds, your basis, and any column (f) and (g) adjustment in one place. UltraTax CS determines the holding period from the acquisition and sale dates and prepares Form 8949 with the return, so you can keep proceeds tied to the 1099-DA while basis follows your records, and your team can focus on the judgment calls.
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