The 2026 tax filing season marks the first year in which U.S. crypto brokers were required to issue Form 1099-DA to the Internal Revenue Service and to taxpayers. Approximately 70.4 million Americans — 30% of the adult population — now hold cryptocurrency, according to Security.org's 2026 Consume...
The 2026 tax filing season marks the first year in which U.S. crypto brokers were required to issue Form 1099-DA to the Internal Revenue Service and to taxpayers. Approximately 70.4 million Americans — 30% of the adult population — now hold cryptocurrency, according to Security.org's 2026 Consumer Report. For every one of them who sold or traded digital assets in 2025, the IRS now receives a matched record of gross proceeds.
The problem: brokers were not required to report cost basis for 2025 transactions. That means millions of 1099-DA forms arrived at IRS processing centers showing proceeds — and nothing else. The IRS treats any unreported or unmatched proceeds as taxable gain until the taxpayer proves otherwise. The resulting compliance gap has triggered a cascade of automated notices, a 758% spike in IRS warning letters to crypto holders, and the deployment of a new audit instrument — the Historical Digital Asset Form — that demands lifetime disclosure of every exchange, wallet, and DeFi protocol a taxpayer has ever used, under penalty of perjury.
This report examines the mechanics of the basis gap, the enforcement infrastructure the IRS has built around it, and the structural risks it creates for the estimated 50 million Americans who hold Bitcoin alone.
Form 1099-DA became mandatory for the 2025 tax year. Under final regulations published by the IRS in June 2024, custodial brokers — exchanges like Coinbase, Kraken, Gemini, and others — were required to report gross proceeds from digital asset sales and exchanges to both the taxpayer and the IRS. The broker deadline for issuing these forms was February 17, 2026.
The form covers proceeds from sales, swaps, and certain transfers. It does not cover DeFi protocol interactions, self-custody wallet activity, or cross-chain bridges — at least not yet. The IRS has signaled that decentralized front-ends remain outside the broker definition following the SEC's April 2026 guidance exempting certain DeFi interfaces from broker-dealer registration.
For the 2025 tax year, the scope is limited to custodial platforms. But within that scope, the IRS now has automated matching capability: every 1099-DA is filed electronically with the IRS, and the agency's Automated Underreporter (AUR) system compares reported proceeds against what appears on the taxpayer's Form 8949 and Schedule D.
If a taxpayer's return does not include proceeds that appear on a 1099-DA, the system generates a CP2000 notice — an automated proposed adjustment that treats the unreported amount as taxable income.
The central compliance problem of the 2026 filing season is not fraud. It is architecture.
Under Section 6045 of the Internal Revenue Code and the final broker reporting regulations, brokers are required to report cost basis only for "covered securities" — assets acquired on or after January 1, 2026. For the 2025 tax year, basis reporting was entirely voluntary. Most brokers chose not to report it.
This creates a structural mismatch. A taxpayer who bought 1 BTC on Coinbase in 2021 for $30,000 and sold it in 2025 for $95,000 will receive a 1099-DA showing $95,000 in proceeds and either a blank or $0 in the basis field. If the taxpayer fails to calculate and report their own basis on Form 8949, the IRS treats the full $95,000 as gain.
The problem compounds for taxpayers who transferred assets between platforms. If an investor purchased ETH on Kraken, moved it to a hardware wallet, then transferred it to Coinbase before selling, Coinbase has no record of the original purchase price. The selling broker cannot report what it does not know.
According to IRS guidance (IRS Notice 2024-56), these are classified as "noncovered" positions. The taxpayer bears full responsibility for calculating and substantiating basis. For assets acquired before 2025 — which, for most long-term holders, means the majority of their portfolio — basis responsibility falls entirely on the individual.
The scale of this problem is not trivial. Of the approximately 70.4 million Americans who hold crypto, a substantial portion have used multiple exchanges, moved assets between wallets, or participated in DeFi protocols that generate taxable events with no centralized record. The IRS's own Tax Gap research has identified cryptocurrency as a significant contributor to underreporting, though precise figures remain unpublished.
The IRS did not wait for the first 1099-DA filing season to begin enforcement. In 2025, the agency issued a 758% increase in warning letters to crypto holders over a 60-day period, according to data from crypto tax platform CoinLedger. The letters — primarily Letter 6174 and Letter 6174-A — range from educational reminders that crypto transactions are taxable to formal notices requesting amended returns.
Letter 6174 is classified as a "no action" notice: it does not require a response and does not allege wrongdoing. Letter 6174-A is more pointed, requesting specific documentation. Both are generated from information the IRS receives from exchanges, blockchain analytics firms, and John Doe summonses served on domestic and international platforms.
The escalation does not stop at letters. In March 2026, tax attorneys identified a new IRS examination instrument: the Historical Digital Asset Form (HDAF). Attached to Form 4564 (Information Document Request) in active audits, the HDAF requires taxpayers to disclose every exchange, wallet, and DeFi platform they have ever used — under penalty of perjury.
The form lists more than 100 named platforms, including defunct exchanges such as FTX and Celsius, hardware wallet providers like Ledger and Trezor, and DeFi protocols. For each platform, the taxpayer must indicate whether they used it, the date of first use, and associated account identifiers. The look-back period extends to the taxpayer's first-ever digital asset activity — there is no statute of limitations on the disclosure requirement within the audit context.
Tax attorney Alex Kugelman of Kugelman Law has advised taxpayers not to sign the HDAF without legal counsel, noting that an inadvertent omission — forgetting a platform used once in 2017, for example — constitutes a sworn false statement to a federal agent and could support penalty escalation or criminal referral.
The HDAF represents a qualitative shift in IRS audit methodology. Previous crypto examinations relied on exchange records and blockchain analytics. The HDAF places the burden of comprehensive disclosure on the taxpayer, creating asymmetric legal risk: the IRS can verify omissions using its own data, but the taxpayer must recall and document every interaction from memory and personal records.
The first-year rollout of Form 1099-DA was not smooth. Major exchanges, including Coinbase and Kraken, reported significant delays in issuing forms. Kraken publicly apologized for delivery delays, citing technical challenges in generating the new form at scale. Some taxpayers reported not receiving their 1099-DA until mid-to-late March 2026, weeks after the broker deadline of February 17.
The IRS addressed this partially through Notice 2024-56, which provides penalty relief for brokers making a "good faith effort" to file and furnish 1099-DA forms correctly and on time during the first year. Brokers will not face penalties for failure to file or furnish forms for calendar year 2025 transactions under this safe harbor.
Taxpayers, however, receive no equivalent relief. The tax filing deadline remained April 15, 2026. Taxpayers who received late or incomplete 1099-DAs were still required to report all digital asset transactions accurately. Those who filed before receiving their forms risked mismatches; those who waited risked late filing penalties.
The enforcement infrastructure extends beyond civil examination. IRS Criminal Investigation (IRS-CI) reported identifying $10.59 billion in financial crimes during fiscal year 2025 (October 2024 through September 2025), a 15.7% increase from the prior fiscal year. Within that figure, $4.5 billion resulted from tax fraud investigations — a 111.8% increase from FY2024.
IRS-CI has approximately 3,000 employees and has expanded its blockchain tracing capabilities through partnerships with analytics firms including Chainalysis and TRM Labs. The unit successfully served multiple John Doe summonses on smaller, decentralized, and international exchanges with U.S. user bases throughout 2025. Notable cases included the sentencing of the founders of Samourai Wallet, a cryptocurrency mixer that processed over $237 million in transactions, to five and four years in prison respectively in November 2025.
TRM Labs' 2026 Crypto Crime Report identified a record $158 billion in illicit crypto flows in 2025, reversing a multi-year decline. While the vast majority of this volume relates to sanctions evasion, fraud, and money laundering rather than tax noncompliance, the figure underscores the scale of enforcement attention directed at the crypto sector.
Fraud penalties in crypto audit cases can reach 75% of the underpayment. In cases involving willful evasion, fines can reach $250,000 and prison sentences up to five years.
The basis gap is scheduled to narrow — partially — with the 2026 tax year. Starting January 1, 2026, brokers are required to report cost basis for "covered" digital assets alongside proceeds on Form 1099-DA. Returns for 2026 transactions, filed in April 2027, will be the first to include matched proceeds-and-basis reporting from brokers.
However, this applies only to assets acquired on or after January 1, 2026, on the same platform where they are sold. Pre-2026 holdings and assets transferred between platforms will remain noncovered. For long-term holders — the demographic most likely to have significant unrealized gains — the basis gap persists indefinitely unless they can independently substantiate their acquisition costs.
The IRS has also signaled interest in expanding the broker definition to include decentralized exchanges and DeFi front-ends, though final rules have not been issued. The Treasury Department's proposed rulemaking on DeFi broker reporting, initially expected in 2025, remains pending.
The 2026 tax filing season is the first in which the IRS has automated, matched reporting of cryptocurrency transactions at scale. The structural decision to phase in proceeds reporting before basis reporting created a compliance gap that falls disproportionately on individual taxpayers — particularly long-term holders and those who have used multiple platforms.
The enforcement apparatus surrounding this gap is substantial: automated matching systems, a 758% increase in warning letters, a new perjury-backed audit instrument, and a criminal investigation unit that identified over $10 billion in financial crimes last fiscal year. The IRS is not speculating about crypto tax compliance. It is building infrastructure to enforce it.
For the 70.4 million Americans who hold digital assets, the message is arithmetical: the IRS now has one side of every custodial transaction. The taxpayer must supply the other side — or the full proceeds become taxable gain by default.