How DOC Inmate Number Search Works

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

If someone you love is in federal prison, the number you need is a BOP register number — eight digits written as five, a hyphen, and three more, like 12345-678. The federal system does not issue “DOC numbers”: DOC stands for Department of Corrections, the name states give their prison agencies, and a number issued by a state prison system will not find anyone in federal custody.

That one distinction solves most failed searches. Below is what the federal number actually is, who assigns it, what the digits mean, how it differs from every other number attached to a federal case, and what to do when you have a name but no number — or a number but no name.

Federal register number: the facts

What it is called	Register number (also “reg. no.”). Not a DOC number, not an inmate ID number in BOP’s own vocabulary
Format	Five digits, a hyphen, three digits — eight digits total (PS 5800.19 at p. 38)
What the last three digits are	The U.S. Marshals Service judicial code (PS 5100.08 at p. 34)
Who assigns it	The U.S. Marshals Service, when the person first enters USMS custody (PS 5800.19 at p. 38)
Documented on	Form USM-129 and/or BP-A0377, Prisoner Remand (PS 5800.19 at p. 38)
How long it lasts	Through the entire commitment and during any period of supervision (PS 5800.19 at p. 38)
Can a person have two?	No. “In no case is an inmate allowed two register numbers” (PS 5800.19 at p. 39)
Governing policy	Program Statement 5800.19, Receiving and Discharge Manual, effective 7 May 2026
Where the number appears	Mail addressing, deposits, phone and email lists, visiting paperwork, every administrative remedy form

Currency stamp: policy verified against Program Statements 5800.19 (7 May 2026), 5800.15 (1 Jan. 2009), 5100.08 CN-3 (6 May 2026) and 5265.14 (5 Apr. 2011) as of 7 September 2026. A Program Statement is the Bureau’s own operating instruction — agency policy, not law.

“DOC number” is state vocabulary; the federal word is “register number”

People arrive at this page having typed “DOC number,” “inmate ID number,” or “prison number,” because those are the phrases that circulate. In the federal system the operative term is register number, and it is the only identifier that will reliably locate a person in Bureau of Prisons custody.

The reason matters. Every state runs its own corrections agency, usually called a Department of Corrections, and each issues its own numbering scheme to people in its custody. Those systems are entirely separate from the federal Bureau of Prisons. They do not share a numbering space, they do not cross-reference, and a number from one will not resolve in the other. If the person you are looking for was prosecuted in a federal district court by an Assistant United States Attorney, they are in the federal system and they have a register number. If they were prosecuted by a county or state prosecutor, they are not in the federal system at all, and nothing on this page will find them.

The Bureau does record other identifiers alongside the register number, and knowing which one you are holding is often the whole problem. The table further down lists them.

One more piece of vocabulary: the Bureau calls the version of the person’s name on the judgment the committed name, and that is the name every record is built on. Program Statement 5800.19 at p. 12 is explicit — “The exact name on the J&C is used as the committed name when admitting an inmate to the designated facility. It must appear on all paperwork and files generated by the Bureau.” A nickname, a married name, or a corrected spelling will not be what the system holds. If you are searching by name and getting nothing, the committed name is the first thing to check.

What the eight digits mean

Take the Bureau’s own sample number, the one it uses in its policy exhibits — 12345-678 (PS 5280.09 at p. 14; PS 7310.04 at p. 21).

• 12345 — the sequential portion, assigned within a block.
• 678 — the U.S. Marshals Service judicial code. The instructions for the Inmate Load and Security Designation form (BP-337) state it plainly: “The U.S. Marshals Service (USM) assigns an eight-digit register number to each inmate with the last three digits denoting the U.S. Marshals’ judicial code. The format is five digits, hyphen, three digits” (PS 5100.08 at p. 34).

The practical consequence is that the suffix reflects where the case entered the system, not where the person is now. A number issued in one district travels with the person through every transfer, every complex, every halfway house, and every year of supervised release afterward. Two people at the same prison will normally have different suffixes; the same person will have the same suffix for life.

Do not try to decode a suffix into a district name from a chart you find online. The Bureau does not publish the judicial-code table, and guessing wrong about where a case originated can send a family to the wrong court clerk and the wrong federal defender’s office. What you can safely take from the suffix is that it is fixed, that it is Marshals-derived, and that it is what makes the eight digits unique.

Applied Insight — Christopher Zoukis, JD, MBA, Managing Director: The single most common mistake families make is treating the register number as a prison ID that changes when the prison changes. It does not. Once you have the number, you have it for the whole sentence and through supervision. Write it down, photograph it, put it in three places. Nearly every task in front of you — mail, money, phone lists, visiting applications, records requests — asks for it before it asks for anything else.

Who assigns the number, and when

The register number is not created by the prison. It is created by the U.S. Marshals Service at the front end, and the Bureau inherits it.

Program Statement 5800.19, section 5.3, at p. 38 sets out the rule: “An inmate’s register number is assigned by the USMS when the prisoner first enters USMS custody and is documented on the USM-129 and/or the BP-A0377, Prisoner Remand form.”

That timing explains a lot. A person arrested on a federal complaint and held pretrial already has a register number, long before any conviction, sentence, or prison designation. The number exists from the moment federal custody begins.

There are four assignment paths, and the same section names all of them:

Situation	Who assigns the number
Ordinary federal arrest or remand	U.S. Marshals Service, at first entry into USMS custody
No opportunity to obtain a number from USMS	The receiving administrative facility, from a block of special-purpose numbers issued by Correctional Programs Branch, Central Office
New commitments at administrative facilities; people received from state institutions en route to a foreign country	Correctional Programs Branch, Central Office
State, territory, commonwealth and military prisoners designated to serve a sentence in a federal institution	The Designation and Sentence Computation Center (DSCC)

Source: PS 5800.19 at pp. 38–39.

That last row is worth pausing on, because almost nobody names the office. The Designation and Sentence Computation Center at Grand Prairie, Texas is where federal designation and sentence computation actually happen — not at the prison, and not at the courthouse. It is also the office that assigns register numbers to boarded state and military prisoners. If you are trying to understand why a designation, a computation, or a number looks the way it does, Grand Prairie is usually the answer, and our explainer on inmate security designation and custody classification walks through how that decision is made.

Before loading anyone, staff run a name search against the Bureau’s records system. If a person already has a number from an earlier commitment, staff must reuse it: “If an inmate has an existing number in the applicable Bureau inmate management system, staff must use this number to admit the inmate and must update the load data. In no case is an inmate allowed two register numbers” (PS 5800.19 at p. 39). A person returning on a supervised-release violation, a new case, or a writ comes back under the number they already had.

The other numbers on a federal case — and what each one will and won’t do

The Bureau records several identifiers for the same person, and families routinely arrive holding the wrong one. The Notice of Release and Arrival instructions in the Correctional Systems Manual enumerate them: register number, FBI number, and a line “intended for other numbers the inmate may have such as: District of Columbia (DCDC/PDID), Immigration/Alien numbers (INS), or State number (STAN)” (PS 5800.15 at p. 79).

Identifier	Who issues it	What it looks like	Will it find someone in federal prison?
BOP register number	U.S. Marshals Service, at first federal custody (PS 5800.19 at p. 38)	Five digits, hyphen, three digits (12345-678)	Yes. This is the identifier the federal system is built on
U.S. Marshals number	U.S. Marshals Service	Same number — the Marshals assign it and the Bureau adopts it (PS 1490.06 at p. 5 calls it “a U.S. Marshals number (register number)”)	Yes — it is not a separate number
FBI number	Federal Bureau of Investigation	Alphanumeric	No. It is a criminal-history identifier the Bureau records (PS 5800.15 at p. 79), not a custody locator
State number (“STAN”)	A state prison agency — this is the “DOC number”	Varies by state	No. Recorded by the Bureau where it exists, but it is not a federal identifier
D.C. number (DCDC / PDID)	District of Columbia	Varies	No. Recorded alongside the register number for D.C. Code cases
Immigration / alien number	Immigration authorities	“A” plus digits	No. Recorded where applicable (PS 5800.15 at p. 79); relevant to the Institution Hearing Program, not to custody search
Court case / docket number	The federal district court, on PACER	e.g. 1:24-cr-00123	No. It identifies the case, not the person in custody. Useful for pulling the judgment
Social Security number	Social Security Administration	Nine digits	No — and never send it to a prison or type it into a search box

The takeaway: only the register number searches. Every other number on this list is something the Bureau writes down about a person; the register number is what the Bureau finds a person by.

The court docket number deserves one extra sentence, because it is genuinely useful for a different job. The Judgment in a Criminal Case — the J&C, the document the sentencing judge signs — is filed on the court’s docket, and a certified copy travels with the person to prison (PS 5800.19 at p. 12). If you have the case number and can get the judgment, you have the committed name spelled exactly as the Bureau will spell it, the sentencing court, and the financial obligations that drive the Inmate Financial Responsibility Program.

If you have a name but no number

This is the ordinary situation, and it has a straightforward sequence.

1. Search the BOP Inmate Locator by name. The Bureau’s public locator accepts a name search and returns the register number, so in most cases you never need to find the number some other way — you find the person, and the number comes with them. Our companion page on how the BOP Inmate Locator works covers what it returns, what it withholds, and what it means when a search comes back empty.

2. Use the committed name, not the everyday name. As above, the Bureau uses the name exactly as it appears on the judgment (PS 5800.19 at p. 12). Try the legal first name rather than a nickname, try a maiden name, and try each half of a hyphenated surname separately — staff themselves are instructed to run “multiple name searches” when a name is hyphenated (PS 5800.19 at p. 39).

3. Read the number off returned mail. A letter that comes back undelivered still carries whatever number was on it, and outgoing mail from the person carries theirs: the Bureau requires every outgoing envelope to show a return address with the inmate’s name, register number, and institution (PS 5265.14 at p. 6). Our page on writing to a federal inmate has the full addressing format.

4. Ask the defense attorney. Counsel of record has the number on the judgment and the docket. This is the fastest route in a case that is still active.

5. Ask the person to send it. If they have already been through intake and Admission and Orientation, they know their number — they will have written it dozens of times by then.

6. If you need more than the number, use the records process. The Bureau will not tell a member of the public much beyond what the law treats as public information about an inmate. Getting further ordinarily requires the person’s written consent or a Privacy Act request with a signed DOJ-361 Certification of Identity; our explainer on FOIA and Privacy Act requests to the BOP sets out the route, and Program Statement 1351.05 at p. 8 is the underlying policy: “Information concerning an individual inmate is not generally available to FOIA requesters unless the inmate whose records are being sought has given a written consent to the disclosure or unless the information has been determined to constitute ‘public information.'”

If you have a number but no name

Working backwards is harder, and the honest answer is that there is no public reverse-lookup that turns eight digits into a person on demand.

What you can do:

• Enter the number in the Bureau’s locator. The public tool accepts a register number as a search key, and it is the only search that treats the number as an index rather than as a label.
• Confirm the format before you conclude the number is wrong. Five digits, hyphen, three digits. A number with a different shape is not a federal register number — it is probably a state number, a booking number, or a docket number, and it will never resolve federally.
• Check whether the digits were transcribed correctly. Handwritten 1 and 7, 0 and 8, and 5 and 6 are the recurring culprits on envelopes and phone lists.
• If the number is genuinely federal and returns nothing, the reason is usually one of a short list — the person is not yet in Bureau custody, has been released, is in community confinement, or is in a category the Bureau does not disclose. Each of those has a different next step, and the inmate locator page walks through them one at a time.

Someone arrested but not yet designated to a prison

A number exists from the first day of federal custody, but a prison does not. Between arrest and arrival at a designated institution, a person can be in a federal detention center, a Bureau administrative facility, or a non-federal contract bed, all while their case is pending.

Three things follow.

Pretrial detainees have register numbers. The Bureau defines a pretrial inmate as “a USMS inmate who is being held subject to pending criminal charges, awaiting trial and/or verdict” (PS 5800.19 at p. 38), and the number is assigned when USMS custody begins, not when a sentence is imposed. Our summary of BOP policy on pretrial inmates covers how that population is handled differently.

Special-purpose numbers exist for the gap cases. Where there is no opportunity to obtain a number from the Marshals, administrative facilities assign from a block issued by Correctional Programs Branch (PS 5800.19 at p. 38). This is why a number occasionally appears before any USMS paperwork does.

A person who is scheduled to self-surrender is not in custody yet. In a voluntary surrender, the courts, U.S. Probation and the Marshals transmit sentencing documents electronically to the DSCC, which enters the designation; staff then access the designation package through the e-Designate system (PS 5140.43 at p. 2). Until the reporting date, there is nothing for a custody search to find. Our explainer on voluntary surrender and unescorted transfers and our guide to preparing for a federal prison sentence both cover that window.

The same is true for people being moved. The Bureau runs a dedicated hub for it — FTC Oklahoma City, an administrative-security federal transfer center — and someone in transit can be recorded at a holdover point rather than at either end of the trip.

What the number is actually for

The register number is not bureaucratic decoration. It is the key on almost every transaction a family will need to complete.

• Mail. Every envelope needs the name and register number. Outgoing mail must carry the same on the return address (PS 5265.14 at p. 6). Details on how to write to a federal inmate and the underlying BOP correspondence policy.
• Money. Funds are addressed to a central processing lockbox in Des Moines, Iowa — never to the prison — and the deposit is matched to the person by name and register number. See how to send money to a federal inmate and the Trust Fund and commissary policy.
• Phone and email. Approved contact lists are built against the person’s record; see inmate phone calls and CorrLinks and TRULINCS email.
• Visiting. Visitor applications are processed against the inmate’s record; see inmate visitation.
• Requests and grievances. The number goes on the BP-A0148 Inmate Request to Staff — the “cop-out” — and on every level of the Administrative Remedy Program.
• Records. The Inmate Central File, the paper and electronic record of the whole sentence, is filed by register number; see BOP central file and records policy.
• Sentence computation. Every computation document is keyed to the number, which matters if a projected release date looks wrong. See challenging a BOP sentence computation and the Sentence Computation Manual.

What changed in 2026

Three developments matter to anyone working with federal numbers and records right now, and no competing page reflects them.

The Receiving and Discharge Manual was reissued on 7 May 2026. Program Statement 5800.19 replaced PS 5800.18 CN-1 (27 Feb. 2025). Its summary of changes lists revisions to inmate personal property, updated fingerprinting requirements and procedures for pretrial inmates, new guidance on whole body imaging devices, and — directly relevant here — “Language limiting the dissemination of sensitive information regarding designations, redesignations, and transfer of inmates to staff not involved with the movement process” (PS 5800.19 at pp. 1–2). The register-number rules themselves carried forward unchanged.

The Bureau moved its core inmate records systems to a cloud platform in August 2026. The Bureau’s own statement describes moving, over a single weekend, the systems that support sentence computation and release-date calculation, custody classification, medical information, and program eligibility (BOP News, “BOP Brings Decades Old Systems Into a Modern Era,” 27 Aug. 2026). This is an IT migration, not a policy change — it creates no right and changes no procedure. It is worth knowing about because the current Receiving and Discharge Manual now says “the applicable Bureau inmate management system” where older policy said SENTRY, and because a records error dated in or around August 2026 has a documented systems change behind it. Background on the underlying system is in our summary of SENTRY, the Bureau’s records system.

Facility names on old records may no longer exist. BOP announced closures and conversions on 1 July 2026 affecting Beaumont FCI Low, Big Spring, La Tuna, the Lexington FMC satellite camp, Petersburg FCI Low and Taft, with Morgantown and Duluth camps converting to Federal Satellite Lows; separately, FCI Dublin, MCC New York, FPC Pensacola and FCI Terminal Island have come off the Bureau’s live facility roster. A register number found on an old letter is still valid; the institution printed under it may not be. Our page on major federal prison closures and deactivations tracks the list.

Where people get stuck with inmate register numbers

“The number I have has too many digits.” Then it is not a federal register number. Federal numbers are five, hyphen, three (PS 5800.19 at p. 38). Booking numbers from a local jail, state numbers, and court docket numbers all have different shapes.

“The number works but the prison is wrong.” Records are updated at the receiving end. The Bureau requires load and admit transactions “within two hours of the inmate’s arrival at the institution” (PS 5800.19 at p. 9) — but that clock starts on arrival, and a transfer can involve holdover stops along the way.

“There are two people with the same name at the same prison.” This is exactly what the number exists to solve. Never send mail or money on a name alone.

“I was given a number by someone who is not the Bureau.” Third-party sites sell “inmate search” services and sometimes hand back stale or invented numbers. The Bureau’s own locator is free. If a number does not resolve there, treat it as unverified.

“I need the file, not the number.” That is a records request, not a search. Start with the FOIA and Privacy Act route and the DOJ-361 form, and understand up front that the Bureau will withhold third-party and security-sensitive material.

“The person is in a protection category.” The Bureau treats certain cases as confidential for protection purposes, and the status, identity and location of Witness Security cases “will not be improperly disclosed” (PS 5180.05 at p. 2). See our summary of the Central Inmate Monitoring system and separatees.

When the number is not the real problem

Most people who land here need eight digits and then get on with mailing a letter. Some do not. If the register number resolves but the projected release date looks wrong, if a designation put someone a thousand miles from home, if a disciplinary finding cost good conduct time, or if a sentence computation appears to have missed prior custody credit, the number was never the issue — the record behind it was.

Elizabeth Franklin-Best, P.C. is a boutique federal criminal defense and appellate firm founded in 2019, working in federal districts and circuits nationwide. Elizabeth Franklin-Best has more than 20 years of federal and appellate criminal defense experience, is admitted to the U.S. Supreme Court and twelve of the thirteen U.S. Courts of Appeals, and has handled more than 330 federal proceedings, over 100 of them appeals. Christopher Zoukis, JD, MBA, leads the firm’s federal prison consulting practice — designation, sentence computation, disciplinary and medical-care advocacy, First Step Act time credits, RDAP, and reentry planning.

If your question is about the record rather than the number, contact the firm at (843) 620-1100. Families who are earlier in the process may find our overview of what families should know about federal prison and our directory of federal facilities useful starting points.

Frequently Asked Questions About Inmate Number Searches

Reviewed for legal accuracy by Elizabeth Franklin-Best, Esq., Principal Attorney·September 2026