By Mike Ring | Blockchain Crypto Tax Prep
Your exchange sold your Bitcoin. The 1099-DA arrived. It shows $47,000 in gross proceeds and $0 in cost basis. You bought that Bitcoin in 2020 for $18,000 and held it on a Ledger for two years before moving it back to the exchange to sell. You know your basis. The exchange does not. The IRS, for now, sees $47,000 in proceeds and nothing to offset it.
This is the transfer basis gap — and it is the most consequential recordkeeping problem in crypto taxation right now.
This guide breaks down exactly why brokers report $0 or “unknown” basis on transferred-in assets, how the covered vs. noncovered framework creates the gap structurally, and what you need to do to reconstruct and substantiate your true basis before IRS matching runs your numbers.
If you want the quick-reference version, start with our 1099-DA missing cost basis solution page. For the full technical picture, keep reading — or visit the Insights hub for related guides.
What Form 1099-DA Actually Reports (And What It Doesn’t)
Form 1099-DA, Digital Asset Proceeds From Broker Transactions, is used by brokers to report proceeds from (and in some cases, basis for) digital asset dispositions to you and the IRS. The key phrase is “in some cases.”
For 2025 transactions, Form 1099-DA generally reports gross proceeds only; it does not have to show the basis or overall gain or loss. The actual tax result requires combining the reported proceeds with the taxpayer’s own records of purchase price.
So the form the IRS receives shows your proceeds. It may or may not show what you paid. Whether or not you receive a Form 1099-DA, you must report all income, gains, and losses from digital asset transactions on your federal income tax return. The form is a floor, not a ceiling. It does not replace your own recordkeeping — it supplements it, imperfectly.
In its early phase, the form will report gross proceeds only, not the investor’s original purchase price, or cost basis. That omission could create confusion for taxpayers and potentially inflate their tax bills if they rely solely on the numbers provided in Form 1099-DA.
This isn’t a bug in the IRS’s system. It is an intentional phase-in. Under the final regulations, brokers must report gross proceeds for transactions effected on or after January 1, 2025, and must report basis on certain transactions effected on or after January 1, 2026. The gap between those two dates — and the structural limits of basis tracking across custody changes — is where the transfer basis gap lives.
The Covered vs. Noncovered Framework: Where the Gap Is Born
Understanding the transfer basis gap requires understanding one concept: covered vs. noncovered assets.
The cost-basis divide under Form 1099-DA follows the covered vs. noncovered framework established in IRC §6045(g) and extended to digital assets by the final broker regulations. A covered digital asset is generally one acquired and held continuously within the same broker account, where the broker’s systems tracked the asset from acquisition through disposition.
If you buy ETH on Coinbase in 2026 and sell it on Coinbase in 2026 without ever touching a self-custody wallet, Coinbase likely has full basis visibility. That’s a covered asset. The 1099-DA should show basis alongside proceeds.
Once custody lineage is broken — through transfers, withdrawals, bridging, or other off-platform activity — the asset is treated as noncovered for broker reporting purposes.
And noncovered means the broker has no obligation to report basis. For noncovered assets (e.g., transferred-in tokens, cross-wallets, assets acquired before 2026, etc.), basis reporting remains optional, though brokers may furnish substitute statements.
Optional. They can report basis. They are not required to. In practice, most don’t — because they can’t. They simply don’t have the data.
Why Self-Custody Creates the Gap
Here is the mechanical reality of self-custody and basis:
When you withdraw crypto from an exchange to a hardware wallet (Ledger, Trezor, Coldcard) or a software wallet (MetaMask, Phantom, Rabby), the exchange records a withdrawal. It does not record a disposition in the taxable sense — transfers between your own wallets are not sales. But the broker’s visibility into that asset’s history ends at the moment it leaves their custody.
If you bought an asset elsewhere, then moved it to an exchange before selling, that exchange may not know your original purchase price. Your statement may still show the full sale amount.
If a client buys Bitcoin on Exchange A and transfers it to Exchange B to sell, Exchange B may not know the original purchase price. Consequently, Exchange B may issue a 1099-DA showing the sale proceeds but listing the cost basis as “unknown.”
This is the scenario playing out across hundreds of thousands of 1099-DAs right now. The exchange selling your asset has no idea:
- When you originally acquired the asset
- What you paid for it
- How many times it moved between wallets before arriving with them
- Whether it passed through DeFi protocols, bridges, or staking contracts along the way
The result is predictable. Example: you bought SOL in 2021 for $3,000, held it in a hardware wallet, moved it to an exchange, and sold for $12,000. Your actual gain is $9,000. But the exchange never saw the purchase, so your Form 1099-DA shows $12,000 in proceeds and $0 in cost basis. The IRS sees $12,000 of profit out of thin air.
That’s not a hypothetical. That’s the current state of the filing season.
The “Unknown” Basis Label Is Not a Correction — It’s a Warning
For the 2025 tax year, brokers are not required to report cost basis. Form 1099-DAs arriving now commonly show “$0,” “Unknown,” or partial basis. If you ever transferred crypto between platforms, the basis trail is broken.
If your exchange reports a transfer-in asset with a $0 cost basis, and you copy that result without fixing it, you may overstate taxable gain.
This is the trap. Someone hands their 1099-DA to tax software, the software sees $47,000 in proceeds and $0 in basis, and calculates $47,000 in taxable gain. That person then pays tax on $29,000 of phantom profit. The IRS is not going to flag you for overpaying — but you should.
Will Transfer Statements Fix This?
Section 6045A of the Internal Revenue Code requires brokers to send “transfer statements” when moving customer assets to another broker, so the receiving broker can inherit the basis information. This is supposed to be the long-term solution.
It is not fully operational yet.
Until transfer-reporting rules under Section 6045A are fully implemented, many transferred assets will be treated as noncovered.
Even after 2026, many digital asset transfers will arrive without the required transfer-statement information. Brokers will not be able to treat those assets as covered, and basis reporting will remain optional for those assets. Moreover, the ability to treat assets as covered hinges on receiving compliant transfer statements from prior custodians. This could limit the portion of assets that are covered.
And that is before you account for the fact that self-custody wallets — by definition — are not brokers and cannot send transfer statements at all. A Ledger hardware wallet does not file 6045A statements. Neither does MetaMask. The transfer basis gap for assets that ever touched self-custody is structural and permanent under the current framework.
This changes for the 2026 tax year (filing in 2027) — brokers will then also report cost basis, but only for “covered” assets: crypto bought and sold on the same exchange after January 1, 2026. For everything acquired before that date or transferred between platforms, the basis gap persists.
How to Reconstruct and Substantiate Your True Basis
This is where the actual work happens. The IRS places the burden of proof on the taxpayer. Filing a return where you claim a cost basis that wasn’t reported by a broker isn’t illegal, but it does place the burden of proof squarely on the taxpayer to provide receipts or trade logs if questioned.
You can assert a basis that differs from what the broker reported. You need to be able to prove it. Here is how we approach it:
Step 1: Pull Every On-Chain Record
Start with wallet addresses. Export transaction history from every wallet — hardware, software, and exchange — that touched the asset in question. On-chain transaction hashes are your primary evidence. For Bitcoin, that means blockchain explorers like mempool.space. For EVM chains, Etherscan and its equivalents. Every transfer-in, transfer-out, swap, and purchase needs to be in the ledger.
Tax preparers should expect to supplement these forms with exported data from exchanges, blockchain explorers, and dedicated portfolio-tracking tools.
Step 2: Match Acquisition Events to Disposal Events
Once you have a complete transaction ledger, you need to identify which specific lots of a given asset were sold at the broker and trace those lots back to their acquisition. For FIFO reporting (the IRS default in the absence of specific identification), this means ordering all acquisition events chronologically and working forward. For specific identification (SpecID), you need documentation that you designated specific lots at or before the time of the sale.
Taxpayers should keep a master list of all platforms and wallets used during the year, note which ones should generate Form 1099-DA, and reconcile those forms against a comprehensive transaction ledger.
Step 3: Gather Supporting Documentation
For each acquisition event you’re asserting as your basis, you need contemporaneous documentation. This means:
- Exchange transaction confirmations showing purchase date, quantity, and price paid
- Email receipts from exchanges (Coinbase, Kraken, Gemini, etc.) for trades executed
- Bank or credit card statements showing the funds used to purchase
- Records of fees paid (commissions and transaction fees are included in basis)
- Screenshots or exports from exchange accounts that no longer issue 1099s (or that have closed)
For digital assets, your cost basis is generally the amount you paid for the asset plus the cost of any commissions or transaction fees.
Step 4: Document the Wallet Chain
To prove that the asset sold at the broker is the same asset you purchased at the original price, you need to trace it through every wallet it passed through. This is the chain-of-custody argument. On-chain records make this auditable in a way that no other asset class can match — every transfer has a permanent, immutable timestamp and transaction hash.
Keep a reconciliation spreadsheet that maps: purchase TX → receiving wallet address → transfer TX → next wallet → transfer TX → exchange deposit address → sale TX. The 1099-DA proceeds line at the end should connect, unbroken, to the original acquisition.
Step 5: Don’t Use the 1099-DA Basis Field in Isolation
In the first year of reporting, brokers generally report gross proceeds, while cost basis may be missing, especially when assets move between wallets, exchanges, chains, or DeFi environments outside broker visibility. Do not prepare your tax return from the 1099-DA alone.
The gross proceeds number on your 1099-DA is likely correct. The basis field is the problem. Use the proceeds, correct the basis, and file Form 8949 with your own documented figures. Where your basis differs from what the broker reported (including $0 or blank), mark the transaction as noncovered and report your reconstructed basis.
For a deeper dive on the exact steps, see our pillar guide on 1099-DA missing cost basis.
The Audit Risk Is Real
The IRS receives a copy of every 1099-DA issued to you. If your tax return does not perfectly match the “Gross Proceeds” reported on these forms, it triggers an automated red flag, potentially leading to a CP2000 notice or a full IRS audit.
That automated matching is already running. The IRS cross-references what brokers report with what appears on your Schedule D and Form 8949. A mismatch — even one where you owe less than the 1099-DA implies — will generate correspondence. The difference is whether you have the documentation to respond.
Relying solely on exchange-generated forms without independent reconciliation often results in overpaying taxes on the full sale price rather than just the capital gain.
If you received a 1099-DA this year and you’ve ever moved crypto to or from a self-custody wallet, the basis number on that form is a starting point at best and a liability at worst. Treat it accordingly.
FAQ: 1099-DA & Self-Custody Cost Basis
1. My 1099-DA shows $0 cost basis. Does that mean I owe tax on the full proceeds amount?
No. A $0 or “unknown” basis on your 1099-DA reflects what the broker was able to report — not your actual taxable gain. If you have documentation showing what you originally paid for the asset, you can (and should) report that basis on your tax return. The burden of proof is on you, so make sure the documentation is solid before filing.
2. I held crypto in a Ledger wallet for three years before sending it to an exchange to sell. How do I prove my basis?
Trace the asset backward: find the original purchase transaction (exchange confirmation, email receipt, transaction export), identify the wallet address it was sent to, then follow the on-chain trail forward to the exchange deposit that preceded the sale. Every hop is recorded on-chain. The transaction hash at each step is your audit trail. Pair that with your original purchase records and you have a defensible reconstruction.
3. Will this problem go away as 1099-DA matures?
Partially. Beginning January 1, 2026, brokers must report both gross proceeds and basis for covered digital assets — generally those acquired after 2025 and held in custody. But the transfer basis gap for assets that touch self-custody will persist structurally, because self-custody wallets are not brokers and cannot generate transfer statements. Any asset that ever leaves a broker’s custody becomes noncovered when it returns.
4. What if the exchange I originally bought from is bankrupt or no longer exists?
This is a real scenario — FTX, Celsius, Voyager, and others. You still have options: look for email confirmations from the time of purchase, export historical CSV files if the exchange’s data is still accessible through bankruptcy proceedings, check bank records for outgoing fiat that corresponds to purchase dates, or use blockchain records of any on-chain deposits. “I can’t find my records” is not a sustainable position with the IRS. Document what you can, note the gaps in writing, and keep any partial evidence.
5. I used DeFi protocols between purchasing and selling. Does that complicate my basis?
Yes, significantly. Transactions conducted on decentralized exchanges, peer-to-peer transfers, certain self-custodied wallet movements, staking rewards, mining income, airdrops, and other on-chain events may not be fully captured by Form 1099-DA. Direct wallet-to-wallet transfers, on-chain swaps through some decentralized protocols, and self-custodied activity may not trigger a Form 1099-DA, even though gains or losses are still fully taxable. Each DeFi interaction — a swap, an LP deposit, a staking event — may be a taxable event that adjusts your basis. You need a full on-chain transaction history for every protocol you touched.
6. Can I just amend my return if the IRS contacts me?
You can, but you want to get ahead of it. Waiting is risky. IRS matching and discrepancy analysis do not pause while taxpayers wait. A CP2000 notice is manageable. An audit that follows a pattern of inconsistent reporting across multiple years is a different conversation. File correctly the first time with your reconstructed basis and documentation in hand.
7. Do I need to request a corrected 1099-DA from my broker?
Not necessarily. The IRS confirmed in Notice 2025-7, Section 4.02, that you do not need the exchange to fix your Form 1099-DA in order to report a different basis on your return. You simply mark the transaction as noncovered, report your own documented basis, and attach the appropriate Form 8949 entries. If the broker’s data is factually wrong in other ways (wrong proceeds, wrong date), that is worth pursuing a correction — but the basis field is yours to complete.
Where to Go From Here
If you’ve moved crypto in and out of self-custody at any point in the past few years — and most active traders have — your 1099-DA basis data needs to be reconciled against your actual records before you file. The form is not wrong, exactly. It just doesn’t know what you know.
The IRS’s official resource page for Form 1099-DA makes clear that you are responsible for reporting all gains and losses regardless of what the form shows. That responsibility includes asserting and documenting your true basis.
We work through this exact problem for clients with complex multi-wallet histories, DeFi activity, and assets that predate the current reporting regime. Our multi-chain transaction processor can reconstruct a complete acquisition-to-disposition ledger and match it against your 1099-DA proceeds line by line.
See our 1099-DA missing cost basis solution page for specifics on how we handle reconstruction, or browse the Insights hub for more guides on DeFi tax, basis tracking, and IRS compliance.
This post is educational and does not constitute tax advice. Every taxpayer’s situation is different. Consult a qualified tax professional — or us — before filing, amending, or responding to IRS correspondence.
Need help with your crypto taxes? Mike Ring and the BCTP team handle the messy stuff — multi-chain DeFi, 1099-DAs that don’t add up, prior-year amendments. Free consult at cryptotaxprep.io or call 410-216-4632.
This isn’t tax advice. Talk to a professional about your specific situation.
