The line between a civil audit and a criminal referral is real, visible, and crossed by a small fraction of cases. But the consequences of missing the signs are severe enough that anyone with sensitive facts - unreported cash, amended history, offshore accounts, false documents anywhere in the file - should know exactly what to watch for.
The Signs
An audit that abruptly goes silent is the classic tell: examiners suspend civil activity when fraud gets referred, so weeks of unexplained quiet after active document requests deserve attention. An examiner who shifts from what happened to why - intent questions, what you knew and when - is gathering elements of fraud, not computing tax. The appearance of a fraud technical advisor in correspondence, summonses issued to your bank or third parties, and interviews of your employees or associates all signal escalation. And two people presenting credentials that say Special Agent are not auditors at all: that is IRS Criminal Investigation, the conversation is evidence, and the only correct response is polite silence and a lawyer's phone number.
Eggshell Audit Conduct
A civil audit sitting on sensitive facts is called an eggshell audit, and it has conduct rules. Nothing false ever gets said or submitted - lying to the IRS during an exam is itself a felony and converts defensible history into fresh crime. Responses stay precise and within scope; volunteering is how eggshells crack. Privilege gets managed deliberately: your accountant can be compelled to testify about what you told them, while attorney-client privilege holds, which is why sensitive audits run through counsel with accountants engaged under privilege where needed.
The Off-Ramps
The system genuinely prefers civil resolution, and voluntary correction before detection remains the most powerful protection available - accurate delinquent filings, properly channeled disclosures, fixing the record through the front door. Which door, and in what order, is precisely the judgment call that requires privileged advice before anything is filed or said. If any paragraph of this article made your stomach drop, call a tax attorney before you talk to anyone else. The first conversation is privileged and free.