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Does Time Spent in Jail Before or After Sentencing Count Toward a Federal Sentence?

Section 3585(b) allows credit for official detention before the sentence commences — but not for time already credited against another sentence.

Post-sentencing • Custody transition Last reviewed: September 6, 2026

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Short answer

Time spent in official detention before a federal sentence commences may receive prior-custody credit under 18 U.S.C. section 3585(b): detention as a result of the offense of conviction, or as a result of another charge for which the person was arrested after that offense. Both branches exclude time already credited against another sentence. The Bureau of Prisons makes the computation after service begins. Prior-custody credit is not good-conduct time and is not a First Step Act Time Credit.

Attorney review pending. This is general education, not legal advice.

Plain-English overview

The direct answer: time in official detention before a federal sentence commences may receive prior-custody credit under 18 U.S.C. § 3585(b), but only in the circumstances the statute describes, and only where the time has not already been credited against another sentence.

The statute has two branches. Detention as a result of the offense for which the federal sentence was imposed, and detention as a result of any other charge for which the person was arrested after the commission of that offense. Both branches carry the same closing limit about time credited against another sentence.

Whether any particular period qualifies is a computation about an individual record. The Bureau of Prisons performs it. CaseSteps does not calculate, estimate or check any period.

Why this matters

The single most common disappointment after sentencing comes from assuming that every day held anywhere is automatically deducted. The statute is narrower than that, and double credit is what the closing clause exists to prevent.

What the important terms mean

'Official detention' is the statutory phrase. It is not a synonym for every restriction on liberty, and courts have addressed its meaning in different settings.

'Has not been credited against another sentence' is the limiting clause. It generally prevents the same period from counting twice, including where a state sentence already received the time.

Prior-custody credit is not good-conduct time, and it is not a First Step Act Time Credit. Those are separate provisions with separate conditions.

Ten things people treat as one thing

Sentence commencement

The date a federal term of imprisonment begins under 18 U.S.C. § 3585(a).

Prior-custody credit

Credit under § 3585(b) for time in official detention before the sentence commenced, computed by the Bureau of Prisons.

Good-conduct time

Up to 54 days per year of the sentence imposed under § 3624(b), based on the Bureau's determination about institutional conduct.

First Step Act Time Credits

A separate credit earned by eligible people for successfully completing assigned qualifying programming, with its own earning and application rules.

A projected release date

A forward-looking figure produced by the Bureau's computation that changes as records change.

A conditional or projected prerelease date

A different figure about community placement, not the end of the term of imprisonment.

Designation

The Bureau's decision under § 3621(b) about which facility a person is assigned to.

Transportation

The physical movement to that facility, which happens separately and on no published timetable.

Federal custody, state custody, primary jurisdiction

Which sovereign holds primary custodial jurisdiction is a separate question from who is physically holding someone on a given day.

A court recommendation and the BOP's authority

A sentencing court may recommend a facility or program; § 3621(b) leaves the designation decision with the Bureau of Prisons.

Common misunderstandings

  • "All time held counts." The statute limits credit to official detention within the two described branches, and excludes time already credited against another sentence.
  • "Time after sentencing while waiting for transfer is a gap." Once the sentence has commenced under § 3585(a), that period is service of the sentence rather than prior-custody credit. Which rule applies depends on the commencement date the Bureau uses.
  • "Prior-custody credit means those days also earn First Step Act credits." They are different systems. Counting toward the sentence and earning credits are not the same thing.
  • "The judge already gave the credit at sentencing." Under United States v. Wilson, the computation is made after service begins, by the Attorney General through the Bureau of Prisons.

Records that may help clarify the issue

  • The judgment and commitment order.
  • The sentence-computation sheet showing prior-custody credit as the Bureau of Prisons has computed it.
  • Records of dates of official detention.
  • State custody records where another sentence may have received the same time.
  • Any detainer information in the file.
  • Do not upload any of these records to CaseSteps, and do not type case numbers, dates or names anywhere on this site. Nothing here accepts files or keeps what you type.

Questions for appropriate Bureau of Prisons staff

  • Which document shows the prior-custody credit currently on my computation?
  • What is the general process for asking for an explanation of that figure?
  • If a period appears to be missing, what records does the Bureau generally need to review it?

Exactly where each statement above comes from — source checked: September 6, 2026

  • Both branches of the credit and the 'has not been credited against another sentence' limit: 18 U.S.C. § 3585(b), official U.S. Code text on GovInfo, read in full September 6, 2026.
  • Commencement as the boundary of the credit period: § 3585(a), same source.
  • The Attorney General, through the Bureau of Prisons, computes the credit after the defendant begins serving the sentence, and a sentencing court cannot make the § 3585(b) computation at sentencing: United States v. Wilson, 503 U.S. 329, 331–337 (1992), official United States Reports text, read September 6, 2026. Wilson involved a request for credit for time in presentence detention by state authorities that a state court later credited against a state term.
  • Where the computation is performed: Bureau of Prisons Sentence Computations page, read September 6, 2026.

What CaseSteps cannot do

CaseSteps does not calculate prior-custody credit, good-conduct time, First Step Act Time Credits, a release date or any other figure.

CaseSteps does not predict a facility, a designation, a transfer date, a transportation route or how long anyone will remain in a detention facility, and it does not say whether sentences run concurrently or consecutively in a particular case or whether a detainer is valid.

The Bureau of Prisons performs the official sentence computation and holds the designation authority. Individual questions belong with appropriate Bureau staff and with qualified counsel.

Questions to discuss with counsel

  • In general terms, which periods of detention can receive prior-custody credit under § 3585(b)?
  • Could any period in my history already have been credited against another sentence?
  • Is a prior-custody credit question raised with the Bureau of Prisons, with a court, or both?
  • What records would be needed to raise a question about a period that appears to be missing?
  • How is prior-custody credit different from good-conduct time and from First Step Act credits here?

Official sources

This is general federal legal education, not legal advice. Procedures and outcomes depend on the facts, the controlling law, court orders and local practices. Confirm deadlines and decisions with qualified counsel.

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