Archive reference note: parts of this topic refer to earlier research records, now listed under open research questions.
18 U.S.C. § 3624(b) — Good Conduct Time
Verification boundary
This module verifies the current nationwide statutory and regulatory calculation structure for good-conduct time (GCT), the First Step Act change, and the historical boundary of Barber v. Thomas. It does not verify a particular prisoner's computation, disciplinary loss, restoration, administrative-exhaustion history, or § 2241 remedy.
Current statutory rule
Section 3624(a) directs the Bureau of Prisons to release a prisoner when the term of imprisonment expires, less credit toward service of the sentence provided by § 3624(b). 18 U.S.C. § 3624(a)
A prisoner serving more than one year, other than a life term, may receive up to fifty-four days of GCT for each year of the sentence imposed by the court, subject to the Bureau's determination of exemplary compliance with institutional disciplinary regulations. 18 U.S.C. § 3624(b)(1)
“Up to” is consequential: the statute does not promise the maximum award. A sentence of one year or less and a life term fall outside this authorization.
If the Bureau determines that the prisoner did not satisfactorily comply during the relevant year, the prisoner receives no GCT or a lesser amount the Bureau determines appropriate; the Bureau also must consider high-school-diploma progress, and credit not earned may not later be granted. 18 U.S.C. § 3624(b)(1)
Subject to § 3624(b)(2), the statute directs that credit for the last year of a term be credited on the first day of the last year. 18 U.S.C. § 3624(b)(1)
That timing sentence does not eliminate partial-final-year proration. The current regulation separately addresses both proration and the anniversary-period mechanics.
GCT awarded under § 3624(b) after enactment of the Prison Litigation Reform Act vests on the date the prisoner is released from custody. 18 U.S.C. § 3624(b)(2)
Current regulatory calculation
For offenses committed on or after November 1, 1987, 28 C.F.R. § 523.20(b)(1) directs the Bureau to project the maximum possible GCT from the imposed sentence while recognizing that the projected release date can change during incarceration. 28 C.F.R. § 523.20(b)(1)
The Bureau awards prorated GCT for a partial final year of the sentence imposed. 28 C.F.R. § 523.20(b)(2)
This corrects the legacy statement that the First Step Act's timing change replaced proration. The 2022 final rule expressly chose proration for a partial final year.
Under the regulation, an inmate may receive up to fifty-four days on each anniversary date; last-year credit is awarded after the final anniversary period unless the final year is complete, in which case it is awarded on the first day of that final anniversary period. 28 C.F.R. § 523.20(b)(3)
For an offense committed on or after April 26, 1996, the regulation sets a maximum of fifty-four days per imposed-sentence year when the literacy condition is met and forty-two days when it is not, subject to the regulation's final-removal-order exception. 28 C.F.R. § 523.20(d)(2)–(3)
The regulation permits GCT reduction for qualifying disciplinary sanctions or failure to comply with applicable literacy requirements. 28 C.F.R. § 523.20(a)
Actual loss, disallowance, forfeiture, and restoration require the disciplinary record, the offense-date branch, and the current rules in Parts 541 and 544; they are not calculated by this module.
First Step Act change and historical rule
The First Step Act changed GCT from a time-served calculation to a sentence-imposed calculation, made the amendment applicable to offenses committed before, on, or after enactment except offenses before November 1, 1987, and the change took effect when the risk-and-needs system was released on July 19, 2019. First Step Act § 102(b), 132 Stat. 5210–11; BOP First Step Act FAQ
The correct dividing fact is therefore amendment coverage—especially offense date—not whether a particular day of the sentence was served before July 19, 2019. Covered computations were recalculated under the amended rule.
Barber v. Thomas upheld the Bureau's time-served method under the pre-First Step Act text, but the First Step Act superseded that calculation rule for covered current sentences. Barber v. Thomas, 560 U.S. 474, 476–87 (2010); First Step Act § 102(b)
Good-conduct-time credit under § 3624(b) is distinct from First Step Act time credits earned through recidivism-reduction programs and applied under §§ 3632(d)(4) and 3624(g). Good Conduct Time Credit Under the First Step Act, 87 Fed. Reg. 7938, 7941 (Feb. 11, 2022)
Computation audit checklist
- Obtain the judgment, statement of reasons if relevant, and the Bureau sentence-computation sheet.
- Record the offense date, imposed term, and whether the sentence is life or no more than one year.
- Separate GCT from prior-custody credit, RDAP reduction, First Step Act time credits, and prerelease-placement dates.
- Check the maximum projection, each disciplinary adjustment, literacy status, anniversary periods, and partial-final-year proration.
- Do not switch to the historical Barber formula merely because some custody occurred before July 19, 2019.
- Preserve the Bureau's actual calculation and administrative record before researching exhaustion and a possible § 2241 challenge.
Decision path
flowchart TD
A["GCT computation question"] --> B{"Offense on or after Nov. 1, 1987?"}
B -->|"No"| C["Current § 523.20 branch does not apply; research old-law credit"]
B -->|"Yes"| D{"Term more than one year and not life?"}
D -->|"No"| E["Outside § 3624(b)(1) GCT authorization"]
D -->|"Yes"| F["Project up to 54 days per imposed-sentence year"]
F --> G["Prorate partial final year"]
G --> H["Apply conduct, literacy, and offense-date rules"]
H --> I["Compare Bureau computation and records"]
Matters not yet verified in this module
- Old-law credit for offenses before November 1, 1987 and D.C. Code credit.
- Particular disciplinary procedures, restoration standards, and due-process claims.
- Administrative-remedy deadlines, exceptions to exhaustion, proper § 2241 respondent, venue, and available relief.
- Interaction with prior-custody credit, aggregated sentences, RDAP, and First Step Act time credits in a particular computation.
Those matters remain open in data/coverage_matrix.yaml; this bounded correction does not validate the legacy file as a whole.
Claim-level source records
CLM-GCT-001 · verified_current
Section 3624(a) directs the Bureau of Prisons to release a prisoner when the term of imprisonment expires, less credit toward service of the sentence provided by § 3624(b).
- jurisdiction
- federal_nationwide
- procedural posture
- sentence_computation
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- Weekend and holiday release mechanics are not included.
- researcher notes
- Direct paraphrase of § 3624(a).
Authorities: 18 U.S.C. § 3624
CLM-GCT-002 · verified_current
A prisoner serving more than one year, other than a life term, may receive up to fifty-four days of GCT for each year of the sentence imposed by the court, subject to the Bureau's determination of exemplary compliance with institutional disciplinary regulations.
- jurisdiction
- federal_nationwide
- procedural posture
- good_conduct_time_calculation
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- Offense-date and literacy rules must also be applied.
- researcher notes
- Direct paraphrase of § 3624(b)(1).
Authorities: 18 U.S.C. § 3624
CLM-GCT-003 · verified_current
If the Bureau determines that the prisoner did not satisfactorily comply during the relevant year, the prisoner receives no GCT or a lesser amount the Bureau determines appropriate; the Bureau also must consider high-school-diploma progress, and credit not earned may not later be granted.
- jurisdiction
- federal_nationwide
- procedural posture
- good_conduct_time_award
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- Actual disciplinary and literacy determinations require the record and regulations.
- researcher notes
- Direct statutory conditions.
Authorities: 18 U.S.C. § 3624
CLM-GCT-004 · verified_current
Subject to § 3624(b)(2), the statute directs that credit for the last year of a term be credited on the first day of the last year.
- jurisdiction
- federal_nationwide
- procedural posture
- good_conduct_time_calculation
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- Current regulation separately controls partial-final-year proration and anniversary mechanics.
- researcher notes
- Statutory timing text, not a no-proration claim.
Authorities: 18 U.S.C. § 3624
CLM-GCT-005 · verified_current
GCT awarded under § 3624(b) after enactment of the Prison Litigation Reform Act vests on the date the prisoner is released from custody.
- jurisdiction
- federal_nationwide
- procedural posture
- good_conduct_time_vesting
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- Earlier offense-date branches may have distinct annual vesting rules under the regulation.
- researcher notes
- Direct paraphrase of § 3624(b)(2).
Authorities: 18 U.S.C. § 3624
CLM-GCT-006 · verified_current
For offenses committed on or after November 1, 1987, 28 C.F.R. § 523.20(b)(1) directs the Bureau to project the maximum possible GCT from the imposed sentence while recognizing that the projected release date can change during incarceration.
- jurisdiction
- federal_nationwide
- procedural posture
- good_conduct_time_projection
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- This does not calculate an individual release date.
- researcher notes
- Current 2025 CFR text cross-checked to 2022 final rule.
Authorities: 28 C.F.R. § 523.20
CLM-GCT-007 · verified_current
The Bureau awards prorated GCT for a partial final year of the sentence imposed.
- jurisdiction
- federal_nationwide
- procedural posture
- good_conduct_time_calculation
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- Exact proration and rounding require the Bureau computation.
- researcher notes
- Corrects the legacy no-proration implication.
Authorities: 28 C.F.R. § 523.20
CLM-GCT-008 · verified_current
Under the regulation, an inmate may receive up to fifty-four days on each anniversary date; last-year credit is awarded after the final anniversary period unless the final year is complete, in which case it is awarded on the first day of that final anniversary period.
- jurisdiction
- federal_nationwide
- procedural posture
- good_conduct_time_calculation
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- All awards remain subject to conduct and literacy conditions.
- researcher notes
- Direct paraphrase of § 523.20(b)(3).
Authorities: 28 C.F.R. § 523.20
CLM-GCT-009 · verified_current
For an offense committed on or after April 26, 1996, the regulation sets a maximum of fifty-four days per imposed-sentence year when the literacy condition is met and forty-two days when it is not, subject to the regulation's final-removal-order exception.
- jurisdiction
- federal_nationwide
- procedural posture
- good_conduct_time_award
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- The 1994-1996 branch and Part 544 literacy definitions require separate application.
- researcher notes
- Direct paraphrase of § 523.20(d)(2)-(3).
Authorities: 28 C.F.R. § 523.20
CLM-GCT-010 · verified_current
The First Step Act changed GCT from a time-served calculation to a sentence-imposed calculation, made the amendment applicable to offenses committed before, on, or after enactment except offenses before November 1, 1987, and the change took effect when the risk-and-needs system was released on July 19, 2019.
- jurisdiction
- federal_nationwide
- procedural posture
- good_conduct_time_recalculation
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- D.C. Code and pre-November 1987 rules are outside this claim.
- researcher notes
- Public Law supplies amendment, effectiveness condition, and applicability; BOP official source supplies release date of the assessment system.
Authorities: First Step Act of 2018, Pub. L. No. 115-391, § 102(b), 132 Stat. 5194, 5210–11; Federal Bureau of Prisons, First Step Act Frequently Asked Questions — Good Conduct Time
CLM-GCT-011 · verified_historical
Barber v. Thomas upheld the Bureau's time-served method under the pre-First Step Act text, but the First Step Act superseded that calculation rule for covered current sentences.
- jurisdiction
- federal_nationwide
- procedural posture
- good_conduct_time_calculation
- classification
- historical
- last verified
- 2026-08-24
- known limitations
- Barber remains relevant to the former statutory text, not the current covered calculation.
- researcher notes
- Historical holding and statutory supersession separated.
Authorities: Barber v. Thomas, 560 U.S. 474 (2010); First Step Act of 2018, Pub. L. No. 115-391, § 102(b), 132 Stat. 5194, 5210–11
CLM-GCT-012 · verified_current
The regulation permits GCT reduction for qualifying disciplinary sanctions or failure to comply with applicable literacy requirements.
- jurisdiction
- federal_nationwide
- procedural posture
- good_conduct_time_reduction
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- Part 541 procedure, sanction validity, and restoration are outside this claim.
- researcher notes
- Direct paraphrase of § 523.20(a).
Authorities: 28 C.F.R. § 523.20
CLM-GCT-013 · verified_current
Good-conduct-time credit under § 3624(b) is distinct from First Step Act time credits earned through recidivism-reduction programs and applied under §§ 3632(d)(4) and 3624(g).
- jurisdiction
- federal_nationwide
- procedural posture
- sentence_credit_classification
- classification
- binding
- last verified
- 2026-08-24
- known limitations
- The separate time-credit eligibility and application rules are outside this module.
- researcher notes
- Explicit distinction in the 2022 final rule preamble.
Authorities: 28 C.F.R. § 523.20