IRS Criminal Investigations (IRS-CI): How Criminal Tax Cases Are Built

By Elizabeth Franklin-Best, Esq., and Christopher Zoukis, JD, MBA

By the time most people learn they are the subject of an IRS criminal investigation, the government has been building its case for months. If a special agent has contacted you, or you sense that a civil audit has quietly changed direction, bring an IRS criminal investigation lawyer into the picture immediately — what you do in the first days often shapes whether the matter ends in a declination or an indictment. At Elizabeth Franklin-Best, P.C., we defend individuals and businesses in federal criminal tax investigations nationwide.

IRS Criminal Investigation — IRS-CI — is the law-enforcement arm of the IRS, and its special agents build criminal tax cases methodically and patiently. Understanding how that process works, where it is going, and what is at stake at each stage is the foundation of an effective defense.

Criminal tax defense is document work, element work, and judgment work, and our practice is built around all three. Elizabeth Franklin-Best, our principal attorney, holds a 2026 Best Lawyers in America recognition as a “Best Lawyer” in Appellate Practice and a Chambers USA 2026 ranking in Litigation: White-Collar Crime & Government Investigations. When a criminal tax investigation surfaces, we start by fixing its true posture — audit, referral, or grand jury — and then build the defense around willfulness, the numbers, and the government’s burden. We bring genuine reach to that work: our principal attorney, Elizabeth Franklin-Best, has appeared in more than 330 federal proceedings, over 100 of them appeals, across all twelve federal circuits and the United States Supreme Court. To put that analysis to work on your situation, schedule a paid, one-hour initial consultation with our team.

IRS Criminal Investigations: Quick Answer

Question	Answer
What is IRS-CI?	IRS Criminal Investigation — the law-enforcement division of the IRS, staffed by special agents who investigate criminal tax and related financial crimes.
How do criminal tax cases start?	The classic route is a civil-audit referral after a revenue agent finds a firm indication of fraud, but most modern cases arrive from U.S. attorney’s offices, other federal agencies, and financial-data analysis.
What does a special agent’s visit mean?	That you are likely a subject or target of a criminal investigation. A special agent is a criminal investigator, not a civil auditor.
What should I do first?	Do not give an unprepared interview, preserve all records, and consult an experienced criminal tax attorney before saying anything substantive.
How does our firm help?	We defend IRS-CI investigations nationwide — representation starts with a paid, one-hour initial consultation devoted to pinpointing where the investigation stands and what to protect first.

Key Takeaways

• IRS-CI is the criminal law-enforcement arm of the IRS; its special agents build criminal tax cases, while revenue agents conduct civil audits.
• A civil audit becomes a criminal referral when the examiner finds a firm indication of fraud — though IRS-CI’s FY2025 data shows most new cases now come from U.S. attorney’s offices, other agencies, and financial data rather than audits.
• IRS-CI opened 2,792 investigations in FY2025 and reported an 89% conviction rate in its prosecutions.
• The IRS may not run a criminal investigation under the cover of a civil audit.
• Revenue agents generally have no duty to warn a taxpayer that an audit may have criminal potential — but they may not affirmatively deceive.
• The contents of existing records are generally not privileged, but the act of producing them can be — a distinction that drives subpoena strategy.
• A special agent’s contact signals that you are likely a subject or target; the interview is designed to obtain admissions.
• A criminal tax investigation can run a long time before it becomes visible, and it ends in either a declination or a prosecution.
• An “eggshell audit” — a civil audit hiding criminal exposure — requires great care, because audit statements can be used criminally.
• What you do in the first days of an investigation can change its entire trajectory.

What Is IRS Criminal Investigation (IRS-CI)?

IRS Criminal Investigation, known as IRS-CI, is the law-enforcement division of the Internal Revenue Service. It is important to understand that the IRS has two very different sides. Its civil side conducts examinations — audits — through revenue agents, whose job is to determine the correct amount of tax owed. Its criminal side is IRS-CI, whose special agents are federal criminal investigators carrying badges and credentials, trained to build cases for prosecution.

IRS-CI investigates criminal violations of the Internal Revenue Code — tax evasion, filing false returns, failure to file, employment tax crimes — and a wide range of related financial crimes, including money laundering and currency-reporting offenses. Its special agents are among the most experienced financial investigators in federal law enforcement, and IRS-CI has a high conviction rate in the cases it recommends for prosecution. The IRS does not pursue a criminal case lightly; when it does, it pursues it seriously.

For anyone who learns that IRS-CI is involved, the threshold point is simple but vital: this is no longer about how much tax is owed. It is a criminal investigation aimed at proving a willful crime beyond a reasonable doubt, and it should be treated that way from the first moment.

IRS-CI Enforcement in FY2025: What the Numbers Show

Each December, IRS-CI publishes an annual report, and the FY2025 report describes an agency that has grown leaner without becoming less dangerous. Special agents opened 2,792 new investigations during the fiscal year and forwarded 2,043 prosecution recommendations, which produced 1,726 informations and indictments. The conviction rate in concluded prosecutions was 89%. Of the 1,613 defendants sentenced in IRS-CI cases, 76% received prison time, with an average of 49 months to serve.

Two details in the FY2025 data matter for defense planning. First, the agency identified $4.49 billion in tax fraud — alongside $6.10 billion in other financial crime — while spending 63.3% of its direct investigative time on tax cases, so the core tax mission remains dominant even as IRS-CI lends agents to narcotics and task-force work. Second, staffing fell from 3,474 employees in FY2024 to 3,143 in FY2025, including roughly 2,189 special agents. A smaller agency picks its cases more selectively — and a selective agency is one that can sometimes be persuaded, with the right factual presentation, that a particular matter does not belong in the criminal system.

One more number deserves attention: only about 3% of FY2025 investigations originated from IRS civil referrals. U.S. attorney’s offices (29%), other federal agencies (27%), and IRS-CI’s own field intelligence (19%) supplied most new cases, with FinCEN bank-data filings adding 12%. A criminal tax case today is as likely to grow out of someone else’s prosecution or a suspicious-activity report as out of your audit — which is why exposure to federal tax crimes has to be assessed against the whole financial picture, not just the examination file.

How a Criminal Tax Case Develops

A criminal tax case moves through a series of stages, and knowing where a matter sits within that progression is essential to defending it.

A case typically begins when IRS-CI develops information suggesting a tax crime — often from a referred civil audit, but also from a whistleblower, a related criminal case, a return preparer investigation, or data analysis. IRS-CI first evaluates that information, and if it is promising, opens a formal criminal investigation in which the taxpayer becomes the subject. The special agent then builds the case — gathering records through summonses and subpoenas, interviewing witnesses, analyzing finances, and, where possible, interviewing the subject.

When the investigation is complete, the special agent prepares a detailed report recommending prosecution or closure. That recommendation is reviewed within IRS-CI and, if it moves forward, referred to the Tax Division of the Department of Justice, which independently reviews the case and decides whether to authorize prosecution. Only after that authorization does the case proceed to a United States Attorney’s office, a grand jury, and a potential indictment.

This multi-layered process has two important implications. First, it is slow — a criminal tax investigation can run for a long time before it becomes visible to the subject. Second, it has multiple decision points, and at several of them the matter can be declined. A defense that engages early can sometimes influence those decision points before an indictment is ever returned.

Applied Insight: Because a criminal tax case passes through IRS-CI review and a separate Department of Justice Tax Division review before any charge, there is a real window in which a well-prepared defense submission — addressing willfulness, the tax loss, and the equities — can affect whether the case is authorized at all. That window closes once an indictment is returned.

Primary Investigations, Subject Investigations, and the Special Agent Report

IRS-CI’s own published procedures give the stages of a criminal tax case precise names, and those names tell you how far a matter has progressed. The first stage is a primary investigation — a preliminary evaluation in which a special agent analyzes incoming information to determine whether a tax crime or other financial crime may have occurred. The agent’s front-line supervisor reviews that preliminary work and decides whether to approve further development; if it advances, the special agent in charge of the field office must approve opening a subject criminal investigation. By the time you are the “subject” of an IRS-CI investigation, at least two layers of CI management have already concluded that the evidence justifies a full criminal inquiry.

Throughout the subject investigation, the special agent coordinates with IRS Chief Counsel criminal tax attorneys so that the legal footing of the case is tested as it is built. At the end, one of two things happens: the investigation is discontinued, or the agent prepares a special agent report recommending prosecution. That report then runs a gauntlet the IRS describes publicly: the supervisory special agent, a centralized quality-review team, the assistant special agent in charge, and the special agent in charge each examine it, and any one of them can conclude the evidence does not support charges.

If IRS-CI approves prosecution, tax cases are referred to the Department of Justice Tax Division, while other financial-crime cases go directly to a United States Attorney’s office. The Tax Division conducts its own independent review under its published criminal tax case procedures, and defense counsel can ordinarily request a conference before prosecution is authorized — a structured opportunity to argue willfulness, tax-loss, health, and policy considerations to the lawyers who decide whether the case goes forward.

Applied Insight: Every review layer between the special agent and the grand jury is an audience, and each audience asks a slightly different question — the quality reviewer asks whether the proof holds together, while the Tax Division asks whether the case serves uniform national enforcement policy. A defense submission tuned to the right audience at the right layer is worth far more than a generic denial of wrongdoing.

From Civil Audit to Criminal Investigation

The most familiar path into a criminal tax case runs through a civil audit. A revenue agent examining a return may encounter what the IRS calls a “firm indication of fraud” — affirmative signs that the taxpayer did not merely make a mistake but acted to deceive. Under the Internal Revenue Manual, the revenue agent is then required to suspend the audit and refer the matter to IRS-CI. The civil examination stops; a criminal investigation begins.

The law places limits on how this transition may occur. In United States v. Tweel, 550 F.2d 297 (5th Cir. 1977), the Fifth Circuit held that a taxpayer’s consent to an IRS examination of records is invalid under the Fourth Amendment when it is induced by an agent’s deceit, trickery, or material misrepresentation — there, a revenue agent’s misleading silence about the Justice Department’s role in a supposedly civil audit — and that evidence obtained through such deception must be suppressed. The principle endures: the government may not dress a criminal tax investigation in the clothing of a routine examination and use the taxpayer’s cooperation against him.

But there is an equally important limit on the other side. Tweel itself reaffirmed that a revenue agent’s mere failure to warn a taxpayer that an audit could turn criminal is not fraud — a suppression motion requires clear and convincing proof of an affirmative misrepresentation, or silence in the face of a direct question that could only mislead. An agent who simply keeps working the file violates nothing; the line is crossed only by affirmative misrepresentation. That asymmetry is exactly why the warning signs of a transition matter so much.

The “Eggshell Audit” Problem

One of the most dangerous situations in tax practice is the “eggshell audit” — a civil audit of a return that the taxpayer knows contains serious problems, perhaps even fraud, that the revenue agent has not yet discovered. The audit looks routine, but it sits on a fragile shell: one wrong move can crack it open into a criminal referral.

The danger is twofold. Statements and documents provided in a civil audit can be used in a later criminal case. And a taxpayer who, during an audit, lies to the revenue agent, alters records, or obstructs the examination can create entirely new crimes — independent of whatever was on the original return. An eggshell audit must be handled with extraordinary care, because the goal is to resolve the civil examination without converting it into a criminal case and without generating fresh criminal exposure. This is a situation where experienced counsel should be involved before the next contact with the agent, not after.

Applied Insight: In an eggshell audit, the instinct to be helpful and cooperative — to explain, to hand over whatever is asked, to smooth things over — is precisely the instinct that creates danger. Truthful, careful, counsel-managed responses are essential; improvised explanations and selective document production are how civil audits become criminal cases.

The Special Agent Interview

For many people, the first unmistakable sign of a criminal tax investigation is a special agent appearing, often without an appointment and often in a pair, asking to “ask a few questions.” This is not a casual conversation. The special agent interview is a planned investigative step, conducted by trained criminal investigators who have usually already gathered substantial information.

When a special agent interviews a person they consider a subject, the agent typically provides a form of advice — identifying the criminal nature of the investigation and noting the right not to answer questions and the right to consult an attorney. That advice is meaningful, and it should be heeded. You are not required to answer a special agent’s questions, and you are entitled to have counsel.

The reason an unprepared interview is so hazardous is specific to tax crime. Every tax crime requires willfulness, and willfulness is proven largely through the defendant’s own words. An off-the-cuff explanation — meant to be helpful, or to make the problem go away — can supply the very element the government most needs. The safest course, almost without exception, is to be polite, decline to be interviewed on the spot, take the agent’s contact information, and call a lawyer.

Documents, Subpoenas, and the Act-of-Production Doctrine

Criminal tax investigations are document cases, so the constitutional rules governing document demands carry enormous practical weight. The starting point is Fisher v. United States, 425 U.S. 391 (1976): the Fifth Amendment protects against compelled testimonial self-incrimination, not against the disclosure of private information, so the contents of records you prepared voluntarily — returns, ledgers, correspondence — are generally not privileged no matter how damaging they are. But Fisher also recognized that the act of producing records communicates facts of its own: handing documents over tacitly concedes that they exist, that you possess or control them, and that they are authentic. Where those implicit admissions would themselves be testimonial and incriminating, the act of production is privileged even though the papers’ contents are not.

United States v. Hubbell, 530 U.S. 27 (2000), shows how much that protection can matter. After Webster Hubbell produced 13,120 pages of records under a grant of act-of-production immunity, prosecutors used what they learned to build a new indictment — and the Supreme Court held the prosecution barred, because assembling documents responsive to a broad subpoena forces a person to use the contents of his own mind, and the government may make no derivative use of that compelled testimony. The doctrine has a limit: where the government already knows the documents exist, knows where they are, and can authenticate them independently, production adds nothing testimonial — the “foregone conclusion” rationale — and the privilege falls away.

In practice, this body of law shapes every response to an IRS summons or grand jury subpoena: which records must be produced, which demands can be resisted, and when immunity or negotiation should precede any production at all. The privilege belongs to individuals — business entities and the custodians of their records stand on very different footing — so the analysis for a sole proprietor’s personal files differs sharply from the analysis for a corporation’s books. This is precise, technical work, and it is one of the places where bringing in white-collar defense counsel early changes outcomes.

What an IRS-CI Investigation Means for You

If IRS-CI is investigating you, it is worth understanding your status precisely. In federal investigations, a person is generally described as a witness, a subject, or a target. A witness has information but is not themselves under suspicion. A subject is someone whose conduct is within the scope of the investigation. A target is someone the government believes it can charge. Status can change as an investigation develops, and understanding where you stand shapes every strategic decision.

Other signs can indicate an investigation is underway: a revenue agent who abruptly stops contact, third parties — your bank, your accountant, your business associates — reporting that they received IRS summonses, or a grand jury subpoena arriving for records. Each is a reason to involve counsel immediately. The earlier a defense is engaged, the more it can do — preserving evidence, managing communications, dealing with the agent, and, where appropriate, presenting the defense’s view of the case before a charging decision is made.

Defense Strategy in a Criminal Tax Investigation

No two criminal tax investigations are alike, and no lawyer can promise a result. But effective defense work in this setting follows recognizable lines:

• Establish where the case stands. Determine whether the matter is a civil audit, a referred criminal investigation, or further along, and identify the client’s status.
• Control communications. Route all contact with the IRS through counsel and stop unprepared interviews and informal explanations.
• Preserve everything. Secure records and documents; destroying or altering anything creates new and serious crimes.
• Build the willfulness defense. Develop the evidence of good faith, reliance on professionals, complexity, error, or hardship that bears on the central element.
• Test the government’s proof. Examine the tax loss calculation, the method of proof, and the strength of the evidence on each element.
• Engage the decision points. Where appropriate, present the defense’s case to IRS-CI or the Department of Justice Tax Division before a charging decision.
• Manage parallel exposure. Coordinate the criminal defense with any civil audit, civil penalty, or related proceeding.

The right strategy depends entirely on the facts and the stage of the case. Our role is to determine where the investigation stands, protect the client at every step, and press every legitimate defense — during the investigation, at the charging stage, in pretrial motions, at trial, and on appeal.

What to Do If a Special Agent Contacts You

If an IRS-CI special agent contacts you, a few steps protect your position. Be polite, but do not agree to an interview on the spot — you are not required to answer questions. Do not consent to searches of your home, office, devices, or records without advice. Do not sign anything. Take the agent’s name and contact information. Say clearly that you will have an attorney get in touch, and then end the conversation.

Just as important is what not to do. Do not destroy, alter, or “organize” any records — that can create obstruction and evidence-tampering charges far more serious than the underlying tax issue. Do not contact witnesses or co-workers to coordinate accounts. Do not call the agent back to “clear things up.” And do not file amended returns or delinquent returns in a panic without counsel, because those filings are new statements that can be used. Then call an experienced IRS criminal investigation lawyer promptly.

Why Work With Elizabeth Franklin-Best, P.C.

Defending an IRS-CI investigation requires fluency in two languages at once: the accounting language of returns, ledgers, and tax-loss computations, and the legal language of willfulness, privilege, and suppression. We work in both, and we apply them at the stage where they matter most — before a charging decision is made.

Elizabeth Franklin-Best leads the defense. Best Lawyers in America 2026 names her a “Best Lawyer” for Appellate Practice, and Chambers USA 2026 ranks her for Litigation: White-Collar Crime & Government Investigations — recognition earned in exactly the kind of high-stakes federal litigation a criminal tax case can become. She is admitted to the United States Supreme Court and all twelve federal circuit courts of appeals, appears pro hac vice in district courts nationwide, and wrote Reversing Your Criminal Conviction. Christopher Zoukis, our Managing Director, contributes focused insight on federal sentencing and the Bureau of Prisons — perspective that informs the risk calculus from the first meeting. Together we defend individuals, professionals, and business owners at every stage of a criminal tax investigation. That experience spans hundreds of federal matters in the district courts and the courts of appeals, and it is concentrated where an IRS-CI case is most often decided: in the careful, document-driven advocacy that precedes a charge rather than the spectacle that follows one.

No defense lawyer can promise you a declination, and we will not pretend otherwise. What we offer is a disciplined investigation-stage defense: an honest read of your exposure, control over every contact with the government, and advocacy at each of the review layers described above. If IRS-CI has touched your life — a visit, a subpoena, a suddenly silent auditor — schedule a paid, one-hour initial consultation and let us establish where things actually stand.

Talk With an IRS Criminal Investigation Lawyer

Criminal tax cases are often won quietly, at decision points most people never see — the supervisor weighing a primary investigation, the reviewer reading a special agent report, the Tax Division lawyer deciding whether to authorize charges. Arriving at those decision points prepared takes time, which is why the day to involve counsel is today. Book your paid, one-hour initial consultation to begin the work.