Short answer: Letter 6173 says the IRS thinks you may not have reported crypto correctly and asks you to fix it or explain. It is not an audit. A CP2000 is a specific proposed tax change based on a mismatch, such as 1099-DA proceeds with no cost basis. Both have deadlines.
| Letter 6173 | CP2000 | |
|---|---|---|
| What it is | Voluntary compliance letter (IRS.gov lists it with 6174 and 6174-A) | Notice of underreported income (IRS Topic 652) |
| Is it an audit? | IRS says no, not an examination | Not an audit; a proposed adjustment |
| What you do | Follow the letter: amend or file returns, or explain why you're compliant | Agree, or disagree with a signed statement and documents |
| Extension | Possible, per instructions in the letter | Per the notice |
Crypto-specific tips
- A CP2000 caused by missing cost basis can often be answered by rebuilding basis. See fixing missing 1099-DA basis.
- Rebuild your history in one tracker before you respond. CoinLedger (code CRYPTOTAX10 for 10% off) and Koinly both produce Form 8949 and audit reports. Affiliate links; disclosure.
- Send responses by trackable mail. The IRS says it doesn't acknowledge receipt.
Big amounts or several years? Firms that say they handle these letters: IRS crypto letter help. This page is not legal advice.
FAQ
Is Letter 6173 an audit?
No. The IRS voluntary compliance letters page, which lists Letter 6173, says the inquiry isn't an audit or an examination. You still need to follow the letter's instructions.
Is a CP2000 a bill?
No. Per IRS Topic 652 a CP2000 proposes changes because income reported to the IRS doesn't match your return. You can agree, or disagree with a signed statement and documentation, by the response date.
Can I email or fax my response?
Generally no for voluntary compliance letters, unless your letter specifically says fax or email is available (IRS.gov).