The 30-Year Miscalculation
Under 18 U.S.C. § 3624(b), federal prisoners are entitled to earn up to 54 days of good time credit per year for good behavior. Simple enough — except the Bureau of Prisons didn't calculate it that way.
For three decades, the BOP calculated good time credits based on time actually served, not the sentence imposed — resulting in approximately 47 days per year instead of 54. The difference: roughly 7 days per year, or 70 days on a 10-year sentence, or 140 days on a 20-year sentence.
Courts repeatedly challenged the BOP's calculation method. The Supreme Court finally addressed the issue in Barber v. Thomas (2010), allowing the BOP's method to stand — but the First Step Act of 2018 went around the Court entirely and just changed the law to say what most people thought it said all along: 54 days.
What the First Step Act Changed
Section 102(b) of the First Step Act amended 18 U.S.C. § 3624(b) to clarify that good time credits are calculated based on the sentence imposed, not time served. This change:
- Applied retroactively to all federal prisoners currently serving time
- Required the BOP to recalculate every eligible prisoner's release date
- Resulted in thousands of prisoners being released earlier than expected in early 2019
Who Is Eligible for Good Time Credits?
Good time credits are available to federal prisoners who:
- Are serving a sentence of more than one year
- Have demonstrated good behavior (no serious disciplinary violations)
- Are not excluded by their offense type (terrorism, sex offenses, and certain other offenses are excluded)
Disciplinary infractions can result in forfeiture of good time credits. However, credits can also be restored if the prisoner demonstrates subsequent good behavior.
How to Check If the Calculation Is Correct
Every federal prisoner has a projected release date calculated by the BOP. This date should reflect the correct 54-day per year good time calculation. Here's how to verify:
Step 1: Get the Sentence Monitoring Computation Data (SENTRY Report)
This BOP document shows the full calculation of the release date — sentence imposed, start date, good time credits earned, projected release date. The prisoner can request it from their case manager, or family members can sometimes obtain it through the BOP's online inmate locator.
Step 2: Do the Math
The calculation should be: sentence in days × (54/365) = maximum good time credits. For a 10-year sentence: 3,650 days × (54/365) = 540 days maximum (if no infractions).
If the calculation uses a lower number or calculates credits based on time served rather than sentence imposed, the calculation may be wrong.
Step 3: File an Administrative Remedy If Incorrect
If the calculation appears incorrect, the prisoner should:
- File a BP-8 (informal resolution) with unit staff
- If unresolved, file a BP-9 formal grievance with the warden
- Appeal to the Regional Director (BP-10) if needed
- Final appeal to the BOP Central Office (BP-11)
After exhausting administrative remedies, a habeas petition under 28 U.S.C. § 2241 can be filed in federal district court challenging the calculation.
Earned Time Credits vs. Good Time Credits
These are two different things and it's easy to confuse them:
- Good Time Credits: Automatic credits for good behavior. 54 days/year maximum. Applied to reduce the length of incarceration.
- Earned Time Credits (ETCs): Credits earned by completing approved programs. Can be applied toward earlier transfer to a halfway house or home confinement — not reduction of the sentence itself.
A prisoner can accumulate both simultaneously. They work toward different things but together can significantly reduce the amount of time spent in a federal facility.
How CaseMatchAI Can Help
If you believe good time credits have been miscalculated, CaseMatchAI can help you find federal court decisions where prisoners successfully challenged BOP calculations — the legal arguments that worked, the courts that agreed, and the outcomes that were granted.