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What Is the Difference Between Good-Conduct Time, First Step Act Time Credits, the Second Chance Act, and RDAP?

Separate the rules often shortened to “85 percent,” “15 percent off,” or “15 days a month.”

Federal custody • Sentence computation topics Last reviewed: September 6, 2026

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Short answer

Prior-custody credit, good-conduct time, First Step Act Time Credits and Second Chance Act prerelease placement are four separate mechanisms with separate purposes, requirements and decision-makers. They are commonly confused because all four can affect how a federal sentence is served. CaseSteps explains the general differences between them. It does not calculate any credit, estimate a release date or determine whether a particular person qualifies; those are matters for the Bureau of Prisons and qualified counsel.

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

Plain-English overview

Prior-custody credit, good-conduct time, First Step Act Time Credits, and Second Chance Act prerelease placement are different mechanisms. They have different purposes, requirements, and decision-makers.

Being held in a detention center does not automatically mean the time fails to count toward the sentence. The person’s legal custody status, when the federal sentence commenced, whether detention time was credited elsewhere, and which type of credit is being discussed all matter.

Dated rule change — checked September 6, 2026

Through September 29, 2026, the existing version of 28 C.F.R. § 523.42(a) remains the currently effective regulatory text. It ties the start of First Step Act Time Credit earning to the date the person arrives, or voluntarily surrenders, at the designated Bureau of Prisons facility.

Effective September 30, 2026, revised § 523.42(a) states: “An eligible inmate begins earning FSA Time Credits after the inmate’s term of imprisonment commences.” The amendment removes the language that tied commencement to arrival or voluntary surrender at the designated Bureau facility.

This does not mean credits begin automatically merely because a sentence was imposed. The person must still be eligible and must successfully complete assigned, approved evidence-based recidivism-reduction programming or productive activities. The change does not promise retroactive credits and does not establish any individual release, placement or transition date. Implementation guidance and practices may change. Check the current regulation and current Bureau of Prisons guidance.

The same rule revises 28 C.F.R. § 523.44(a)(3). It states that the paragraph does not bar application of First Step Act Time Credits for a person serving a sentence imposed in a foreign country when the U.S. Parole Commission has determined an equivalent U.S. Code sentence under 18 U.S.C. § 4106A.

The document is an interim final rule and request for comments, published August 31, 2026 at 91 FR 55740, effective September 30, 2026. Comments are accepted through September 30, 2026. The Bureau invoked the Administrative Procedure Act’s good-cause provisions rather than using prior notice and comment.

This page describes a regulation that changes on September 30, 2026. Confirm the current regulation and Bureau of Prisons guidance before relying on it.

The person must still successfully complete assigned qualifying programming or productive activities.

Comparing the mechanisms

Sentence commencement

Under 18 U.S.C. § 3585(a), a federal sentence generally begins when the defendant is received in custody awaiting transportation to the facility where the sentence will be served or voluntarily arrives to begin serving the sentence. State custody, federal writs, concurrent sentences, and other overlapping custody situations can be considerably more complicated.

Prior-custody credit

Under § 3585(b), certain qualifying official detention before the federal sentence begins may receive credit, but not when the same time has already been credited against another sentence. BOP performs the official calculation. The name of the building—federal detention center, county jail, or contract facility—does not by itself determine whether the time counts.

Good-conduct time

For qualifying imprisonment terms of more than one year, other than life sentences, a person may receive up to 54 days for each year of the sentence imposed, subject to BOP’s disciplinary-compliance determination and applicable law.

Supervised release

Supervised release is a term ordered by the court that generally begins after release from imprisonment. It is not good-conduct time, prior-custody credit, or a program credit.

About good-conduct time, stated clearly

  • It is not “15 days per month”
  • It does not require First Step Act programming
  • It is not an automatic promise of exactly 15% off
  • CaseSteps will not calculate it

First Step Act Time Credits

  • An eligible person earns 10 days of First Step Act Time Credits for every 30 days of successful participation in evidence-based recidivism reduction programs or productive activities assigned based on the person’s risk and needs assessment
  • An additional five days for each 30-day period requires a Bureau of Prisons determination of minimum or low recidivism risk and that the person has not increased their risk of recidivism over two consecutive assessments
  • BOP has reported that risk and needs reassessments generally occur at least every 180 days. That helps explain why people sometimes describe a six-month waiting period. The legal rule, however, is based on two consecutive assessments—not a guaranteed number of days or months
  • Not everyone is eligible to earn the credits
  • Earning credits and applying credits are separate determinations
  • Credits may be applied toward prerelease custody or, in qualifying circumstances, earlier transfer to supervised release
  • Earlier transfer to supervised release based on these credits cannot exceed 12 months
  • Credits are not automatically earned simply because a person is in custody

“15 days a month” is not a universal benefit. The accurate general description is 10 days—or, for some qualifying people, 15 days—for every 30 days of successful participation in assigned qualifying activities.

Second Chance Act prerelease placement

  • This is an individualized BOP prerelease-placement process
  • Residential Reentry Center consideration may extend to as much as 12 months
  • That does not guarantee 12 months
  • Ordinary Second Chance Act home-confinement authority is generally limited to the shorter of 10% of the imprisonment term or six months unless another authority applies
  • BOP has described qualifying FSA credits and SCA consideration as cumulative or “stackable,” but conditional dates remain conditional
  • Users must not add the periods together themselves

RDAP, and how the four mechanisms differ

Good-conduct time

A possible reduction administered by the Bureau of Prisons under 18 U.S.C. § 3624: up to 54 days for each year of the sentence imposed for qualifying terms, subject to statutory and BOP requirements. It is not First Step Act programming credit and is not an automatic percentage.

First Step Act Time Credits

Earned through successful participation in assigned qualifying programs or productive activities. Earning and application are separate determinations, and recidivism-risk assessments matter to both.

Second Chance Act prerelease placement

Individualized Bureau of Prisons placement in community conditions such as a Residential Reentry Center (RRC), often called a halfway house, for up to 12 months. The ceiling is not a guarantee.

RDAP

The Residential Drug Abuse Program is a Bureau of Prisons treatment program. Any early release associated with completing it comes from a separate statutory authority with its own eligibility rules, and it is not the same as First Step Act Time Credits.

Myth and fact

Myth: “Everyone automatically gets 15% removed.”

Fact: Good-conduct time is up to 54 days per year of the sentence imposed for qualifying terms and remains subject to BOP’s determination.

Myth: “Everyone earns 15 days per month for programming.”

Fact: The ordinary First Step Act earning rate is 10 days per 30 days of successful qualifying participation. The additional five days requires separate statutory conditions.

Myth: “Time in a detention center never counts.”

Fact: The facility name does not answer the question. Sentence commencement, official detention, custody status, prior credit, and the type of credit involved must be distinguished.

Myth: “A conditional date is a guaranteed release date.”

Fact: Conditional dates depend on continuing eligibility, participation, assessments, official calculations, and placement decisions.

Every question below is for discussion with counsel and appropriate BOP staff—not an eligibility determination or administrative filing.

Questions to confirm

  • On what date does BOP currently show the federal sentence commencing?
  • What prior-custody credit is reflected?
  • Was any custody time credited to another sentence?
  • What good-conduct time is currently reflected?
  • Is the person eligible to earn First Step Act credits?
  • What assigned activities are currently producing credits?
  • Which credits have been earned?
  • Which earned credits have been applied?
  • What risk assessments affect the application of credits?
  • Does the September 30, 2026 rule affect this record?
  • What conditional dates appear in the official record?
  • Who should review a possible discrepancy?
  • What administrative process applies if an official computation is disputed?

Official sources

Organize this with the Custody Transition Organizer

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Open the Custody Transition OrganizerWhat Happens After Federal Sentencing?

Continue to Release and Reentry

Prerelease placement and supervised release are separate processes with separate decision-makers.

How Do the Second Chance Act, RRC Placement, and Home Confinement Work?What Is Federal Supervised Release?

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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