The SIU call: cooperation, counsel, and the line between them

What a Special Investigations Unit actually is

A Special Investigations Unit, or SIU, is the anti-fraud arm every sizable payer runs. When the SIU rather than a claims examiner contacts you, the file has usually crossed from routine payment review into a fraud-and-abuse inquiry — set off by a billing pattern their analytics flagged, a whistleblower, or a member complaint. You often cannot tell from the first call how serious it is, so it is safest to treat the contact as if it could be the serious kind.

SIU is not a RAC, a TPE, or a routine audit

It helps to place the SIU against the reviews that are not it. Medicare's routine integrity tools are educational or error-focused: Targeted Probe and Educate reviews 20 to 40 claims per round with teaching between rounds and escalates only after three failed rounds 1Ref 1Centers for Medicare & Medicaid Services (2026).Targeted Probe and Educate (TPE).That Targeted Probe and Educate is an educational, error-focused Medicare review (20-40 claims per round, education between rounds, escalation after three failed rounds), contrasted with a fraud-focused SIU inquiry., and Recovery Audit Contractors run post-payment review with full appeal rights through the five-level Medicare appeals process 2Ref 2Centers for Medicare & Medicaid Services (2026).Medicare Fee for Service Recovery Audit Program.That Recovery Audit Contractors run post-payment review with appeal rights through the five-level Medicare appeals process, a routine error-focused program distinct from an SIU fraud inquiry.. An SIU inquiry is different in kind — it is looking for intent, not just error, and its findings can feed a fraud referral rather than a simple recoupment of overpayments.

The first call: get everything in writing

Do not conduct a substantive interview on the spot. On the first contact, be courteous, confirm who is calling and for which payer, and ask for the request in writing — the specific claims, the records sought, and the deadline. An informal phone conversation is still on the record, and an off-the-cuff explanation of a billing choice can harden into an admission you cannot walk back. Take the request in writing, then respond deliberately rather than defensively.

Cooperation versus counsel — where the line sits

Cooperation and self-protection are not opposites, but they meet a line. Producing the records a payer is contractually entitled to is cooperation; narrating your intent on a recorded call, or signing a statement the investigator drafted, is where a solo practice gets hurt. The signals that move an SIU contact toward the counsel threshold are concrete: the word fraud or false claims in any letter, a request to interview you under oath or on the record, an extrapolated demand, a threatened payment suspension, or any hint that the records themselves are in question.

When those appear, weigh healthcare counsel before you answer substantive questions. Naming when counsel is genuinely warranted is informing the decision, not making it for you — but a solo practice rarely gains from improvising answers to an investigator trained to elicit them.

What they will ask for, and how to hand it over

An SIU records request typically seeks the full chart for named dates of service: your notes, the signed treatment records, consents, and anything authenticating that the service happened as billed. Medicare requires services to be authenticated by a handwritten or electronic signature, and a missing signature can sometimes be cured by a formal attestation during review 3Ref 3Centers for Medicare & Medicaid Services (2023).Complying with Medicare Signature Requirements.That Medicare requires services to be authenticated by a handwritten or electronic signature and that a missing signature can be cured by an attestation in review — relevant to how records are prepared for an SIU request. — so confirm your notes are properly signed before you send them, and never add or backdate a signature now. Produce a complete, paginated copy, keep an identical set for yourself, and log exactly what you sent and when.

The stakes behind the call

The reason an SIU contact deserves care is the range of outcomes behind it. A fraud finding can lead to exclusion from federal health programs, after which no federal program may pay for anything you furnish — OIG publishes the exclusion list as the public check 4Ref 4HHS Office of Inspector General (2026).Exclusions Program.That OIG can exclude an individual from federal health programs, after which no federal program payment may be made for services they furnish, with the LEIE as the public check — the exclusion stake behind a fraud finding.. If your own review surfaces conduct that implicates federal fraud laws, OIG's self-disclosure protocol is a defined path to resolve it, often on better terms than waiting to be found 5Ref 5HHS Office of Inspector General (2026).Health Care Fraud Self-Disclosure Protocol.That OIG maintains a self-disclosure protocol for conduct implicating federal health-program fraud laws — the escalation path when the clinician's own review surfaces a real problem.. Which law governs the plan matters too: a self-funded employer plan runs under ERISA rather than state insurance law, which changes both your appeal rights and the payer's leverage 6Ref 6U.S. Department of Labor (2026).ERISA.That self-funded employer plans are governed by ERISA rather than state insurance law, which changes the appeal rights and leverage in a payer investigation.. This is also where a clinician learns how the False Claims Act reaches a solo practice, and how the upcoding patterns payers mine become the spine of a case.

What an SIU inquiry can lead to

An SIU inquiry does not resolve into a single outcome, and knowing the range helps you calibrate the response. At the lighter end, the unit closes the file or issues a recoupment for the specific claims it can document as overpaid. In the middle, it can move to terminate your network participation, ending your in-network status with that payer. At the serious end, it refers the matter to a regulator or to law enforcement, where the False Claims Act and program exclusion come into play.

Because you cannot tell from the first call which path the inquiry is on, treat every response as though it could feed the most serious one. Keep your tone cooperative and your records complete, but assume anything you say or send could later be read by someone building a case rather than closing a file. That assumption costs you nothing if the file closes, and protects you if it does not.

Your first-week sequence

Move in a fixed order the week an SIU makes contact, so nothing slips while you are still deciding how serious it is. The sequence protects both your cooperation and your position, and it keeps you from improvising an answer you cannot take back. Work it top to bottom:

• Get it in writing. Confirm the payer and investigator, then obtain the specific request and deadline in writing before answering anything substantive.
• Preserve and freeze. Lock every record for the named claims exactly as it stands; never edit, add, or backdate a note now.
• Test against the triggers. If fraud language, an under-oath interview, extrapolation, or a payment-suspension threat appears, weigh healthcare counsel before you respond.
• Produce a complete, logged copy. Send exactly what was requested, paginated, with a record of what went out and when.
• Keep your duplicate. Retain an identical set of everything you send.

A parallel Medicare escalation, the higher-stakes UPIC investigation, runs a similar path worth understanding alongside this one.