How does the IRS know about your crypto?

The IRS learns about your crypto mainly from the companies you use. Exchanges and other custodial brokers send it information returns, and the IRS matches them against your tax return. It also has legal tools to demand customer records, and the public nature of most blockchains means activity can often be traced back to a known account.

How does the IRS know if you sold crypto?

Through Form 1099-DA. The IRS says brokers that take possession of customers' digital assets, including custodial platforms, certain hosted wallet providers and crypto kiosks, must file it. Gross proceeds are reported for transactions from January 1, 2025, and cost basis for certain transactions from January 1, 2026. The IRS sends the same information to the taxpayer. How the forms fit together is covered in crypto tax forms.

Matching is the next step. The IRS sends a CP2000 notice when income or payment information from third parties does not match a return. The notice proposes changes, which can raise or lower the tax owed, and asks for a reply. Ignoring it can lead to a bill.

How does the IRS know about crypto gains from earlier years?

For years before the 1099-DA, the IRS has gone to court. A John Doe summons lets it demand records about taxpayers whose names it does not yet know.

• In April 2021, a federal court in Massachusetts authorized a summons to Circle, covering US customers with at least $20,000 of crypto transactions from 2016 to 2020.
• In August 2022, a federal court in California authorized one to SFOX, a crypto prime dealer, for customers above the same $20,000 threshold from 2016 to 2021.

In both cases, the Justice Department stressed that the company was not accused of wrongdoing. The SFOX release said crypto can be hard to trace and that some taxpayers may use it to hide income. Other summonses and IRS letters are covered in does the IRS audit crypto.

Does the IRS know about my crypto in a private wallet?

Not directly from a form. Self-custody wallets and decentralized exchanges are outside 1099-DA reporting, after Congress repealed the DeFi broker rules in April 2025. RSM noted, though, that most of this activity stays visible on public blockchains.

That matters because coins usually pass through a reporting platform at some point, when they are bought or cashed out. Once an address is linked to a known customer, its history can be followed, as explained in can cryptocurrency be traced. The IRS has bought blockchain analytics tools for this work. Decrypt reported in September 2020 that it paid nearly $250,000 for a 12-month, 120-user subscription to one such service.

Your own return is also a source. Every Form 1040 asks whether you received digital assets as a reward or payment, or sold, exchanged or otherwise disposed of them, and the IRS says transactions must be reported even when they produce no gain. Holding crypto or buying it with dollars alone is a No.

Rules differ by country and change often. Check the tax authority or a qualified professional for your own situation.