Prior Custody Credit

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

Does time already served count, and who decides?

Yes, but only within limits, and the judge does not decide it — the Bureau of Prisons does. 18 U.S.C. § 3585(b) gives credit for time in “official detention” before the sentence commences, but only if that time “has not been credited against another sentence.” The Supreme Court held in United States v. Wilson, 503 U.S. 329 (1992), that the computation is made administratively, after the sentence begins.

Key takeaways on prior custody credit

• Two categories qualify. Time served “as a result of the offense for which the sentence was imposed,” and time served on “any other charge for which the defendant was arrested after the commission of” that offense — § 3585(b)(1)–(2).
• The double-counting bar is the whole ballgame. Credit is available only for time “that has not been credited against another sentence.” Most disputes are really arguments about whether a state court already used the same days.
• The judge cannot award it at sentencing. Wilson: “A district court, therefore, cannot apply § 3585(b) at sentencing.” Asking the judge for jail credit is the single most common wasted motion in this area.
• Restrictive bail is not detention. Reno v. Koray, 515 U.S. 50 (1995): a defendant “admitted to bail on restrictive conditions… is ‘released,'” even when the condition is 24-hour residence in a treatment center.
• Primary jurisdiction decides who gets the time. The sovereign that arrests first keeps priority until it releases on bail, dismisses the charges, paroles, or the sentence expires — United States v. Cole, 416 F.3d 894 (8th Cir. 2005).
• A federal writ does not move primary custody. A person produced on a writ of habeas corpus ad prosequendum is on loan; the state still holds them.
• There is a route for state time: the nunc pro tunc designation. BOP must consider a request under Barden v. Keohane, 921 F.2d 476 (3d Cir. 1991) — but is not obliged to grant it.
• Wrong computations are fixed administratively first, through 28 C.F.R. Part 542, and then by habeas. The full sequence is on our bop sentence computation page.

What 18 U.S.C. § 3585(b) actually says

Two subsections do all the work, and they are short. From 18 U.S.C. § 3585, current as of 12 July 2026:

“(a) Commencement of Sentence.— A sentence to a term of imprisonment commences on the date the defendant is received in custody awaiting transportation to, or arrives voluntarily to commence service of sentence at, the official detention facility at which the sentence is to be served.”

“(b) Credit for Prior Custody.— A defendant shall be given credit toward the service of a term of imprisonment for any time he has spent in official detention prior to the date the sentence commences— (1) as a result of the offense for which the sentence was imposed; or (2) as a result of any other charge for which the defendant was arrested after the commission of the offense for which the sentence was imposed; that has not been credited against another sentence.”

Three things follow from that text, and they explain most of what goes wrong.

“Shall be given” is mandatory — for qualifying time. Where the time qualifies, the Bureau has no discretion to withhold it. This is not like residential reentry center placement or a rdap eligibility reduction, where the statute says “may.” Prior custody credit is an entitlement when the conditions are met. The fight is always about whether they are met.

The clock stops when the sentence commences. Subsection (a) fixes that moment: the date the person is received in custody awaiting transportation to, or arrives at, the designated facility. Time before that date is governed by (b); time after it is service of the sentence itself, reduced by good conduct time and, for those eligible, by first step act time credits. Those are different mechanisms with different rules, and conflating them is the source of a great deal of confusion.

The final clause is a bar, not a condition. “That has not been credited against another sentence” removes time from eligibility. It does not add a requirement to prove anything. In practice the Bureau reads the state sentence computation record to see whether the state used the same days, and if the state did, the days are gone.

The second category is wider than people expect

Subsection (b)(2) is routinely overlooked. It covers detention on “any other charge for which the defendant was arrested after the commission of the offense for which the sentence was imposed.” That is not limited to related conduct. If someone commits the federal offense in March, is arrested in July on an unrelated state charge, and sits in custody on that unrelated charge until the federal sentence commences, that time can qualify — subject to the double-counting bar.

The sequencing matters and is easy to get wrong. The arrest on the other charge must come after the commission of the offense of conviction. Detention on a charge for which the person was arrested before committing the federal offense does not fit the subsection.

Who calculates prior custody credit — and why it is not the judge

This is the point almost every reader gets wrong, and it is settled.

In United States v. Wilson, 503 U.S. 329 (1992), the Supreme Court held that “the Attorney General must continue to compute the credit under § 3585(b).” The reasoning is practical:

“After a district court sentences a federal offender, the Attorney General, through BOP, has the responsibility for administering the sentence… Because the offender has a right to certain jail-time credit under § 3585(b), and because the district court cannot determine the amount of the credit at sentencing, the Attorney General has no choice but to make the determination as an administrative matter when imprisoning the defendant.”

And the Court gave a grammatical reason the court cannot do it:

“Section 3585(b) indicates that a defendant may receive credit against a sentence that ‘was imposed.’ It also specifies that the amount of the credit depends on the time that the defendant ‘has spent’ in official detention ‘prior to the date the sentence commences.’… By using these verbs in the past and present perfect tenses, Congress has indicated that computation of the credit must occur after the defendant begins his sentence.”

Hence the sentence that should be printed on the wall of every sentencing courtroom: “A district court, therefore, cannot apply § 3585(b) at sentencing.”

The Attorney General’s authority is delegated to the Bureau of Prisons by regulation — 28 C.F.R. § 0.96, the same delegation provision Wilson cited. In practice the computation is performed by the Designation and Sentence Computation Center.

What the judge can do is separate and worth knowing. A sentencing court can impose a shorter sentence to account for time already served, and it can order a federal sentence to run concurrently with or consecutively to an undischarged term under 18 U.S.C. § 3584. A court’s recommendation about concurrency is also the single most important document in a later nunc pro tunc request. What the court cannot do is compute the credit — and a judgment that purports to award a specific number of days of jail credit does not bind the Bureau’s arithmetic. That distinction is worth raising with counsel before sentencing, which is where our federal sentence mitigation attorney work overlaps with this page.

Prior custody credit: who decides what, and under which authority

The question	Who answers it	Authority	What it means in practice
Does time in official detention count?	Congress	18 U.S.C. § 3585(b)	Mandatory — “shall be given credit” — for time not already credited elsewhere
Who computes it?	The Attorney General, through the Bureau of Prisons	United States v. Wilson, 503 U.S. 329, 334–35 (1992); 28 C.F.R. § 0.96	Not the judge. “A district court… cannot apply § 3585(b) at sentencing”
When is it computed?	After the sentence commences	Wilson, 503 U.S. at 333	The verb tenses in the statute require it. A number given at sentencing is a prediction, not a computation
Is time on restrictive bail “official detention”?	No	Reno v. Koray, 515 U.S. 50, 57 (1995)	“[A] defendant admitted to bail on restrictive conditions… is ‘released'” — even in a 24-hour treatment center
What is “official detention,” then?	Custody of the Attorney General	Koray, 515 U.S. at 58	Credit is “available only to those defendants who were detained in a ‘penal or correctional facility’… and who were subject to BOP’s control”
Which sovereign’s time is it?	The one with primary jurisdiction	United States v. Cole, 416 F.3d 894, 896–97 (8th Cir. 2005)	First to arrest holds priority until release on bail, dismissal, parole, or expiration of sentence
Does a federal writ change that?	No	Pope v. Perdue, 889 F.3d 410, 412–13 (7th Cir. 2018)	A writ of habeas corpus ad prosequendum takes “temporary custody… without acquiring primary custody”
Can state prison time ever count federally?	Sometimes, by designation	Barden v. Keohane, 921 F.2d 476 (3d Cir. 1991); BOP PS 5160.06	BOP must consider a nunc pro tunc request; it is not obliged to grant one
Where do you challenge the result?	BOP first, then a court	28 C.F.R. Part 542; 28 U.S.C. § 2241	Administrative remedies first; then habeas in the district of confinement

BOP Program Statements are internal agency policy, not law. They bind staff, not courts.

What counts as “official detention”

The statute uses the phrase and never defines it. Koray supplied the definition, and it is narrower than intuition suggests.

Koray was ordered confined to a Volunteers of America community treatment center, 24 hours a day, as a condition of bail rather than as a detention order. He sought credit for that time. The Supreme Court said no:

“We hold that the time respondent spent at the Volunteers of America community treatment center while ‘released’ on bail pursuant to the Bail Reform Act of 1984 was not ‘official detention’ within the meaning of 18 U.S.C. § 3585(b).”

The dividing line is legal status, not physical restriction:

“[U]nder the language of the Bail Reform Act of 1984, a defendant suffers ‘detention’ only when committed to the custody of the Attorney General; a defendant admitted to bail on restrictive conditions, as respondent was, is ‘released.'”

And the Court tied “official detention” to the Bureau’s own control:

“[C]redit for time spent in ‘official detention’ under § 3585(b) is available only to those defendants who were detained in a ‘penal or correctional facility,’ § 3621(b), and who were subject to BOP’s control.”

What this means in ordinary cases. Time on pretrial release does not count, however restrictive. Home detention with an ankle monitor as a bail condition does not count. Inpatient treatment entered as a condition of release does not count. A halfway house entered as a bail condition does not count — even though a halfway house entered as prerelease custody at the end of a sentence is service of the sentence. The same building produces opposite answers depending on the order that put the person there.

Applied Insight — Elizabeth Franklin-Best, Esq., Principal Attorney: The place to fight Koray is at the bail hearing, not afterwards. Once someone is “released” on conditions, the months are gone for credit purposes no matter how confining the conditions were, and the argument that the conditions were functionally custodial has been foreclosed since 1995. Where a client faces a real choice between pretrial detention and a restrictive release package, that choice has a sentence-length consequence, and it should be made with the consequence on the table. Justice Ginsburg noted in concurrence that the Court had not foreclosed a due-process argument about whether a defendant elected bail understanding that halfway-house time would earn no credit — that is a narrow and unresolved question, not a strategy.

The double-counting bar and the state–federal overlap

This is where most real disputes live. The bar itself is one clause: credit is available only for detention “that has not been credited against another sentence.” What makes it hard is that in a state–federal case, two sovereigns are keeping their own books.

Primary jurisdiction, in four rules

The doctrine is old and the modern statement is clean. From United States v. Cole, 416 F.3d 894 (8th Cir. 2005):

“As between the state and federal sovereigns, primary jurisdiction over a person is generally determined by which one first obtains custody of, or arrests, the person.”

“Primary jurisdiction continues until the first sovereign relinquishes its priority in some way. Generally, a sovereign can only relinquish primary jurisdiction in one of four ways: 1) release on bail, 2) dismissal of charges, 3) parole, or 4) expiration of sentence.”

That is the whole framework, and it decides the order in which sentences are served. The sovereign with primary jurisdiction gets its sentence served first.

The writ that does not transfer anything

Here is the mechanic that surprises families more than any other. When a person is in state custody and the federal government wants to prosecute, the United States produces them on a writ of habeas corpus ad prosequendum. The person is transported by the U.S. Marshals Service, appears in federal court, may be housed in a federal detention center for months, and may be sentenced there.

None of that moves primary custody. From Pope v. Perdue, 889 F.3d 410 (7th Cir. 2018):

“Using this writ, a sovereign may take temporary custody of a prisoner in the custody of another sovereign, for the purpose of prosecution, without acquiring primary custody.”

Courts describe the arrangement as a loan. The state remains the primary custodian; the federal sentence does not commence; and the time is being credited to the state, not to the federal term. A person can spend a year in a federal facility, wearing federal clothing, and receive not one day of federal credit for it — because on the books they were a state prisoner the whole time.

Pope also supplies the flip side, which is where arguments are won: “In the absence of evidence that the transferring sovereign intended to maintain custody, we presume that the sovereign intended to relinquish it.” Where the state released the person outright to federal authorities rather than lending them on a writ, primary custody may have moved — and the paperwork proves it. The USM-129 form, the writ itself, and the state’s own custody records are the documents that decide these cases.

Willis and Kayfez: the two exceptions BOP applies to itself

Section 3585(b) reads like an absolute bar. BOP does not apply it as one. Its sentence computation policy incorporates two named exceptions, and the designation policy long pointed to them by name: PS 5160.05 — agency policy, not law, in force until September 2026 — directed that on a retroactive designation “a thorough review of jail credit (Willis/Kayfez) must be conducted as outlined in the sentence computation manuals.” Its replacement, PS 5160.06 (3 September 2026), keeps the review but drops the names: “When a nunc pro tunc designation is made, the DSCC conducts a thorough review of jail credit, as outlined in the sentence computation manuals” (at p. 9).

The Willis exception. Willis v. United States, 438 F.2d 923 (5th Cir. 1971), held that where a person “was denied release on bail because the federal detainer was lodged against him, then that was time ‘spent in custody in connection with the [federal] offense.'” The court also noted the arithmetic point that drives the modern policy: state credit “did not help Willis… because his federal sentence is due to expire more than a year after his state terms.”

The Kayfez exception. Kayfez v. Gasele, 993 F.2d 1288 (7th Cir. 1993), addressed credit that is real on paper but worthless in fact. Where concurrent sentences run and the state credit does not actually shorten anyone’s time in custody, the Seventh Circuit held the Bureau’s contrary reading unreasonable:

“It is impossible to have an effective credit of 416 days within the 358. The remaining 58 days credit would shorten the state term, but would not benefit Kayfez except that during 58 days he would be serving only one sentence instead of two concurrent ones.”

How to use this honestly. Both decisions are old, and both construe the repealed predecessor statute (18 U.S.C. § 3568). They matter today not primarily as precedent a court will apply, but because the Bureau has written them into its own sentence computation manual as exceptions it will apply. The practical consequence is concrete: where state and federal sentences are concurrent and the state’s credit is ineffective — because the state term expires first, or because the credit exceeds the gap between the two expiration dates — a request that BOP perform a Willis or Kayfez review is a specific, named, policy-grounded ask. It is not a novel argument. It is a request that the Bureau follow its own manual.

Two situations that reverse the usual answer

When the state sentence is vacated. If the state conviction that consumed the days is later set aside, the premise of the double-counting bar disappears with it. Kayfez addressed exactly this: “[B]y August 22, the concurrent state sentences had been vacated, and it would be unreasonable to consider as a ‘[credit] against another sentence,’ an allowance of credit against a vacated sentence.” A vacatur in state court is therefore a reason to ask the Bureau to recompute — and it is a request that has to be made, because nothing propagates automatically from a state courthouse to the Designation and Sentence Computation Center.

When the transfer to federal custody was itself a mistake. BOP policy addresses the situation where someone produced on a writ was never returned to the state and instead began serving the federal sentence. PS 5160.06 § 7(a) — agency policy, not law — provides that “[w]hen it has been determined an inmate was committed improperly to federal custody and primary jurisdiction resides with a state sovereign (i.e., the inmate was under jurisdiction of the federal sentencing court on the basis of a writ of habeas corpus ad prosequendum), DSCC and institution staff will attempt to return the inmate to state custody.” And it states the consequence in terms: “A return to the state means that the federal sentence should be considered as not having commenced, since transfer to the Bureau was in error” (at p. 8).

That is a rule with two edges. It can undo months a person believed were federal time. It can also, in the right posture, be the answer to why a federal sentence is showing a commencement date that makes no sense against the custody records. Either way it is a reason to read the writ and the USM-129 before accepting the computation.

The nunc pro tunc designation

When the time in question is not presentence detention at all but service of a state sentence, § 3585(b) cannot help — that time was, by definition, credited against another sentence. A different mechanism can.

Under 18 U.S.C. § 3621(b), the Bureau designates the place of imprisonment, and it “may designate any available penal or correctional facility… whether maintained by the Federal Government or otherwise.” That includes a state prison — and it can be done retroactively.

Barden v. Keohane, 921 F.2d 476 (3d Cir. 1991), held that “the federal government has the statutory authority to make the nunc pro tunc designation” and that the Bureau has “an obligation… to look at Barden’s case and exercise the discretion the applicable statute grants.” The court was careful about what it was not deciding: “We do not pass upon Barden’s contention that he is entitled to a favorable exercise of the broad discretion the Federal Bureau of Prisons has.” Review after the Bureau acts “will be limited to abuse of discretion.” Barden remains the decision the Bureau itself names in policy (PS 5160.06 at p. 6).

BOP’s own procedure, from PS 5160.06 — agency policy, not law, dated 3 September 2026. It replaced PS 5160.05 (16 January 2003), moving the decision from the Regional Directors to the Designation and Sentence Computation Center (DSCC) and making the five factors in 18 U.S.C. § 3621(b) the test:

Step	What the policy says
How the request is characterized	“[T]he Bureau considers an inmate’s request for credit toward a federal sentence for time spent in state custody and credited to a state sentence, as a request for a nunc pro tunc designation” (at p. 6)
Who decides	The DSCC Sentence Computation Section Chief “is delegated the Bureau’s authority to designate a state institution for concurrent service of a federal sentence,” and that authority is further delegated to the DSCC Operations Managers (at p. 3). Regional Directors no longer have a role (at p. 1)
What is gathered	“[A] copy of the federal and state judgments,” “the state sentence data record to include jail credit and release dates,” and “any other pertinent information relating to the federal and state sentences” (at p. 6)
The letter to the judge	The DSCC Sentence Computation Section Chief writes to the sentencing court “inquiring as to the court’s position regarding a retroactive designation,” with courtesy copies to the U.S. Attorney’s Office and U.S. Probation Office (at p. 6)
The 60-day rule	“If, after at least 60 days, a response is not received from the federal sentencing court, the DSCC Sentence Computation Section Chief reviews the five factors under 18 U.S.C. § 3621(b) and makes a designation decision”; the person is told the decision in writing (at p. 7)
The governing standard	The five factors in 18 U.S.C. § 3621(b); any response from the sentencing court is considered as part of that review (at p. 7)
The hard limit	“[T]here is no obligation under Barden for the Bureau to grant the request by designating a state institution retroactively” (at p. 6)
A bar	No concurrent designation “if the federal sentencing court has already made a determination regarding the order of service of sentence” — e.g. an express consecutive order (at p. 7)
A Fourth Circuit exception	For people sentenced in the Fourth Circuit between 29 December 2006 and 27 March 2012, the Bureau does not seek the sentencing court’s view and must weigh heavily the state court’s preference for concurrency (at pp. 7–8)
What follows a grant	“[T]he DSCC conducts a thorough review of jail credit, as outlined in the sentence computation manuals” (at p. 9)

Two practical points fall out of that table. First, the sentencing court’s silence is not neutral — it starts a 60-day clock after which the Bureau decides alone, so a letter from the judge is worth more than any argument in the request itself. Second, an express consecutive order is close to fatal, which is why the concurrency language in the judgment is worth fighting for at sentencing rather than litigating afterwards.

Applied Insight — Christopher Zoukis, JD, MBA, Managing Director: The nunc pro tunc request is one of the few places in this system where a well-assembled packet genuinely changes an outcome, because the Bureau is required to consider it and is choosing on a record you can build. What moves it: the federal judgment’s exact concurrency language, the state judgment, the state sentence data record showing precisely which days the state used, and — where it exists — a letter or amended judgment from the sentencing judge saying what was intended. What does not move it: an explanation of why the total sentence feels unfair. And because the request is characterized as a designation request rather than a credit request, it is filed with the Bureau, not with the court.

Reading the sentence computation sheet

The Bureau’s arithmetic is published to the person it concerns, on a document usually called the sentence monitoring computation data sheet, generated in SENTRY. It is the single most useful piece of paper in a computation dispute, and most families have never asked for one.

What to look for, in order:

• The date the sentence commenced. Compare it against the § 3585(a) rule. If it is later than the date the person was received in federal custody to serve the sentence, that is a question.
• Total prior credit awarded, usually expressed as a number of days with the inclusive date ranges that produced it.
• The date ranges themselves. These are where errors live. Look for a gap corresponding to time in a county jail, or a period covered by a writ.
• Any Willis or Kayfez notation, which indicates the Bureau has performed one of the two reviews described above.
• The projected release date, and separately any First Step Act figures — those come from a different instrument, the FSA Time Credit Assessment, discussed on our first step act time credits page.

A computation sheet with a correct commencement date and correct credit ranges is a computation you can then check against good conduct time and, separately, against whatever community placement the second chance act and First Step Act authorities support. Getting the front end right matters more than anything downstream, because every later date is calculated from it.

If the computation is wrong

The remedy has a fixed order, and skipping a step usually costs more time than following it.

Step one — ask, in writing. Raise it with the unit team and Inmate Systems, and ask for the current computation sheet. A material share of credit disputes are clerical: a missing state record, a date range keyed wrong, a jail that never sent its records.

Step two — the administrative remedy program. 28 C.F.R. Part 542 sets out the BP-8 through BP-11 sequence, with deadlines short enough to be lost by accident. The full sequence, the response times, and the rejection traps are on our bop sentence computation page — that page sets out the procedure in full.

Step three — habeas under 28 U.S.C. § 2241. A challenge to the execution of a sentence — including credit computation — belongs in a § 2241 petition, filed in the district of confinement against the warden. Wilson itself contemplated this route, noting that “prisoners have been able to seek judicial review of these computations after exhausting their administrative remedies.” The mechanics of the petition, the immediate-custodian rule, and what happens on transfer are on our 2241 petition page.

A note on timing that matters. In Pope v. Perdue, the Seventh Circuit held that release from prison does not necessarily moot a computation challenge, because a finding of over-incarceration “would carry ‘great weight'” in a motion to reduce a term of supervised release. That is a bridge worth knowing about, and it connects this page to early termination of supervised release.

What this page does not decide

We do not compute anyone’s credit here, and no page should. The categories above are the method; the arithmetic depends on records — state sentence data, jail booking sheets, the writ, the judgment — that no website has. A pattern risk assessment score, a federal home confinement date, and a prior custody credit total are three different numbers produced by three different processes, and adding them up from a web page is how families end up with a date that was never real.

What is worth doing instead is assembling the documents. The state sentence data record showing which days the state used; the federal judgment’s concurrency language; the writ and the USM-129; the booking and release dates from every facility. That file answers the question. Nothing else does.

Why work with Elizabeth Franklin-Best, P.C.

We work on federal sentence computation in every federal district — reviewing computation sheets against the underlying records, assembling nunc pro tunc designation requests, pursuing Willis and Kayfez reviews where the arithmetic supports one, and taking credit disputes through the administrative remedy process and into habeas where they cannot be resolved inside the Bureau.

Elizabeth Franklin-Best, P.C. is a boutique federal criminal defense and appellate firm founded in 2019, with offices in Columbia and Mount Pleasant, South Carolina, serving clients nationwide on an intentionally small caseload. Elizabeth Franklin-Best is admitted to the U.S. Supreme Court and twelve of the thirteen U.S. Courts of Appeals — every regional circuit (1st–11th) plus the D.C. Circuit — and has handled more than 330 federal proceedings, over 100 of them appeals, with sixteen published decisions as counsel of record. Christopher Zoukis, JD, MBA, leads the firm’s federal prison consulting work, is the author of the Federal Prison Handbook and the Directory of Federal Prisons, and serves as Chairman of the Board of the Human Rights Defense Center.

We will not tell you how many days you are owed before we have seen the records. Anyone who does is guessing.

Schedule a consultation

If a release date does not match the time actually served, if months in a county jail or on a federal writ appear nowhere in the computation, or if a state sentence was supposed to run concurrently and does not, those are answerable questions once the file is in front of us.

Schedule a consultation with Elizabeth Franklin-Best, P.C. Our practice is nationwide.

For the wider picture, start at our federal prison early release lawyer hub. For what happens to the placement at the end of the sentence, see federal prison release plan; for the offense-based exclusions that cut off other routes, offenses that preclude rdap; and for the home-detention pilot with its own two-thirds computation, elderly offender home detention.

Frequently Asked Questions About Prior Custody Credit

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