Proffer Agreements and Limited Immunity in Criminal Tax Cases

Written by Sam Brotman, J.D., LL.M. (Taxation), MBA — Managing Attorney, Brotman Law  ·  Updated May 2026

What a Proffer Agreement Is

A proffer agreement is a contract between a defendant or suspect and the government that governs how statements made in a proffer session will be used. It is sometimes called a "Queen for a Day" letter, though that term is colloquial and the documents can vary in their terms. The agreement is drafted by the government — the U.S. Attorney's office or DOJ Tax Division — and the defendant's counsel negotiates it before the session takes place.

The core function of the agreement is straightforward: the government wants information and the defendant wants some measure of protection for providing it. The proffer agreement is the framework that governs the exchange. It typically states that the government will not use the defendant's proffer statements in its case-in-chief, subject to specific carve-outs that are written into the agreement itself.

Proffer agreements are most common when a defendant may have information valuable to the government's broader investigation — co-conspirators, financial structures, offshore accounts, third-party advisors, entity relationships. They are also used when the government wants to evaluate whether a defendant is a credible cooperator before extending a formal cooperation agreement or plea deal. Think of the proffer as the government's audition process for cooperation.

The agreement itself is typically one to three pages. It identifies the parties, describes the scope of the session, and sets out the specific immunity protections and their limits. The limits — the carve-outs — are where the analysis lives.

What Limited Immunity Means — and What It Does Not

The specific protections vary by agreement, but a standard proffer agreement provides three things:

1. The government will not use your proffer statements as direct evidence against you in its case-in-chief.
2. The government will not refer your proffer statements to other agencies for use against you in unrelated proceedings (sometimes included, sometimes not — read the agreement).
3. If the government needs to establish the existence of the proffer session, it may do so, but your statements remain protected.

And there are standard carve-outs. Under virtually every proffer agreement, the government retains the right to:

• Use your proffer statements to impeach you if you testify at trial and your testimony contradicts what you said in the session.
• Use your proffer statements to rebut any defense you present that is directly contradicted by your proffer.
• Use leads developed from your proffer statements to investigate and prosecute you with independently obtained evidence.
• Use your statements if you commit perjury, obstruction, or provide false statements — in which case the agreement is typically void entirely.

The lead-development carve-out is the one that surprises people most. You describe a transaction. The government follows that thread. Three months later, a cooperating witness independently confirms the transaction. That testimony is fair game — it was derived from your proffer, but the government obtained it independently. This is not a hypothetical; it is a standard prosecutorial tool.

The short version: limited immunity protects your words in that room from being read aloud by a prosecutor in front of a jury. It does not protect you from the consequences of everything those words set in motion.

The Immunity Spectrum: Use, Derivative Use, and Transactional

Not all immunity is the same. Understanding where a proffer agreement sits on the spectrum is important context for evaluating what you are — and are not — getting.

A standard proffer agreement provides use immunity only — and only for direct use in the case-in-chief. It does not provide derivative use immunity. That distinction matters enormously. Under a proffer, the government can follow every lead your statements generate and build an independent case using that lead-derived evidence. Under statutory immunity ordered by a court under 18 U.S.C. § 6002, the government would need to show its case predates your compelled testimony. Proffer agreements do not carry that burden.

Transactional immunity — a full bar on prosecution for the covered conduct — is essentially a relic of state law practice. Federal prosecutors do not grant it. If someone is telling you a proffer agreement gives you transactional immunity, that is incorrect.

Queen for a Day Letters

A "Queen for a Day" letter is the colloquial term for a proffer agreement letter, so named because the protections it offers are temporary, conditional, and limited in scope. The phrase comes from the old TV show premise — for one day, you get to be treated like royalty. In the legal context, it means: for the duration of this session, your statements get a measure of protection. That protection ends when the session ends, and it was never as broad as you might have hoped.

The term is used interchangeably with "proffer letter" or "proffer agreement" in practice, though technically the letter sets the terms while the session is the proffer itself. The document you sign before walking in is the Queen for a Day letter. What happens in the room is the proffer session.

Some practitioners distinguish between an informal proffer — a conversation with the government without a written agreement, sometimes called a "reverse proffer" — and a formal proffer session governed by a written agreement. Do not confuse the two. An informal proffer or reverse proffer, where the government shares what it knows with you, carries different dynamics. The government is not bound by any agreement in an informal setting. Counsel should be present regardless.

Inside the Proffer Session

A proffer session is a meeting between the defendant (with defense counsel present), the Assistant U.S. Attorney, and typically one or more IRS Criminal Investigation special agents. In DOJ Tax Division cases, a DOJ Tax trial attorney may attend in addition to or instead of the AUSA. The session is not recorded, but the government takes detailed notes.

Participants typically present:

• AUSA or DOJ Tax trial attorney — leads the questioning, evaluates cooperation potential, makes recommendations on whether to extend a formal cooperation agreement
• IRS-CI special agent — the investigating agent who built the case file; may ask technical questions about transactions, entities, and financial records
• Defendant — answers questions; the entire purpose of the session
• Defense counsel — present throughout; can object, redirect, and advise the defendant in real time; should have reviewed the agreement and prepared the defendant extensively beforehand

Sessions typically run one to three hours, though complex financial cases can run longer — and the government may request follow-up sessions. The format is conversational. The government asks questions; the defendant answers. There is no transcript. The government's notes from the session are internal documents, but in practice, those notes may appear in a prosecution memorandum or be referenced in any subsequent proceeding where the agreement's carve-outs apply.

One thing worth understanding about the dynamic: the IRS-CI special agent in the room has often spent 18 to 36 months building the case file before a proffer is even on the table. They know the financial records, the bank accounts, the entity structures, the third-party witnesses. They are not uninformed. They are evaluating whether your account is consistent with what they already know.

When Proffering Comes Up in Criminal Tax Cases

Proffer agreements arise at a specific stage of a criminal tax investigation — after the government has developed its case to the point where it is evaluating prosecution, and before indictment. By the time a proffer is on the table, IRS Criminal Investigation has typically completed a substantial investigative phase: the special agent report has been written, the case has been referred to the DOJ Tax Division or USAO, and the government is deciding whether to indict, seek a plea, or evaluate cooperation.

The criminal tax statutes most commonly at issue in these cases are:

• IRC § 7201 — tax evasion (felony; up to 5 years per count)
• IRC § 7202 — willful failure to collect or pay over tax, typically employment taxes (felony; up to 5 years)
• IRC § 7203 — willful failure to file a return or pay tax (misdemeanor; up to 1 year, though often charged as a felony pattern)
• IRC § 7206(1) — filing a false return (felony; up to 3 years per count)
• IRC § 7206(2) — aiding and assisting in filing a false return (felony; applies to tax professionals and advisors)

FBAR-related cases — willful failure to file FinCEN Form 114 under 31 U.S.C. § 5314 — are increasingly part of the criminal tax landscape as well, particularly in cases involving unreported foreign financial accounts. The Bank Secrecy Act criminal penalties under 31 U.S.C. § 5322 carry up to 10 years for willful violations. Proffer agreements in FBAR-related cases often overlap with questions about the FBAR quiet disclosure history and whether the taxpayer's civil-side disclosures were accurate.

Understanding the line between tax avoidance and tax evasion is also essential context in any criminal tax case — the government's theory typically depends on characterizing specific conduct as willful evasion rather than aggressive but lawful planning. That distinction shapes what the government wants from a proffer and what a defendant should be willing to discuss.

Grand jury targets and subjects are the most frequent profferers. A target is someone the government believes committed a crime and is likely to be indicted. A subject is someone whose conduct falls within the scope of the investigation but whose status has not been formally resolved. Both can proffer; the analysis differs. A target proffer is essentially a negotiation over whether and on what terms the defendant will cooperate before indictment. A subject proffer may be an attempt by the defendant to demonstrate that their conduct was not willful — a different strategic posture with different risks.

The Strategic Decision: When to Proffer, When Not To

The case for proffering typically involves some combination of:

• The government has a strong case and cooperation may be the only path to a substantially reduced sentence
• The defendant has genuinely valuable information about co-conspirators or the broader scheme that the government does not have
• The government has signaled it is open to a non-prosecution or deferred prosecution agreement if cooperation is credible
• The defendant's exposure on current charges is manageable, but there are related charges or entities the government hasn't pursued yet that cooperation could resolve

The case against proffering typically involves:

• The government's case is weaker than it appears, and a proffer would fill evidentiary gaps the government couldn't fill on its own
• The defendant has limited information to offer — a proffer that produces nothing of value damages credibility and produces no benefit
• The agreement's carve-outs are broad, and the risk of impeachment or lead-derived prosecution is high
• There are third parties — family members, business partners, advisors — whose exposure would be significantly increased by the defendant's proffer statements
• The defendant's account of events is not consistent enough to withstand the government's scrutiny, creating false-statement exposure

The last point deserves particular attention. Walking into a proffer session with an inconsistent or incomplete account is dangerous. If the government's records — bank statements, wire transfers, email, third-party witness accounts — contradict what you say in the room, the agreement's carve-outs kick in. You haven't just failed to cooperate. You've potentially handed the government evidence of consciousness of guilt, inconsistent statements, or false declarations. The proffer session goes from an asset to a liability in a single answer.

Proffering without counsel is not a strategic choice. It is an error. The agreement is drafted by the government. Counsel reviews the specific language, prepares the defendant for the scope and sequence of questions, and is present in the room to manage the session in real time. There is no context in which walking into a proffer session without representation makes sense.

If the Proffer Breaks Down

If a proffer session does not result in a cooperation agreement — or if the government concludes the defendant was not forthcoming — prosecution proceeds. The proffer itself does not immunize the underlying conduct in any way. The government retains everything it had before the session, plus whatever leads the session generated that it can now pursue independently.

There are several ways a proffer can go wrong:

• The defendant is not credible. Inconsistencies between proffer statements and the government's existing evidence undermine any cooperation potential. The session ends; the case proceeds.
• The defendant lies. Making false statements in a proffer session voids most agreements entirely, and exposes the defendant to prosecution for false statements under 18 U.S.C. § 1001 in addition to the underlying charges.
• The defendant has nothing the government wants. If the defendant's information is already known or of no value, the government has little reason to extend cooperation credit.
• The cooperation terms are unacceptable. A proffer is often followed by negotiations about the scope and terms of formal cooperation. If those negotiations fail, the proffer session stands but no agreement results. The government has the leads; the defendant has nothing but limited immunity for the statements themselves.

Post-proffer prosecution is common. The government's case is typically stronger after a proffer — not necessarily because of the statements themselves, but because the statements pointed investigators toward evidence they then developed independently. That is the nature of the lead-development carve-out.

One practical consideration: if a proffer does not result in cooperation, the case does not simply reset to where it was before. The government now knows the defendant's account of events, which it can use strategically throughout the litigation. It cannot put the proffer statement in at trial, but the AUSA who sat in that room heard it. Defense strategy is harder to construct from a starting point of "they already know what we planned to argue."

Voluntary Disclosure and the Proffer Intersection

Criminal tax cases involving offshore accounts frequently present a specific overlap between the voluntary disclosure framework and the proffer process. This is worth understanding as a distinct scenario.

The IRS Voluntary Disclosure Practice — the successor to the Offshore Voluntary Disclosure Program (OVDP) — provides a path to civil resolution for taxpayers who voluntarily come forward before the government opens a criminal investigation. The key word is "before." Once IRS-CI has opened a criminal investigation, voluntary disclosure is no longer available under the standard program.

The complication arises when a taxpayer has made a partial or informal disclosure — sometimes called a quiet disclosure — that falls short of the full voluntary disclosure standard. If that quiet disclosure is identified during a civil exam, the examiner may refer the case to IRS-CI, triggering a criminal investigation. At that point, the taxpayer is a subject or target, the civil disclosure history is part of the government's evidence, and the question of whether to proffer is now on the table.

In these cases, the proffer is often about willfulness — whether the failure to file FBARs or report foreign income was willful or negligent. That is both a factual question and a legal one. The government's theory of willfulness will likely be built around the taxpayer's conduct after the quiet disclosure became apparent — whether they corrected it, what advice they sought, what they told their advisors. A proffer that presents a credible non-willfulness narrative, backed by documentation the government can verify, may be the mechanism for moving toward a civil resolution rather than a criminal one. But that only works if the narrative is true, verifiable, and consistent with the documentary record.

The intersection of voluntary disclosure history and criminal exposure is technically complex. If you are in this situation, the analysis requires a defense attorney with direct experience in both IRS voluntary disclosure and federal criminal tax practice — not just one or the other.