Day-for-Day Credit in Illinois: Rates, Limits, and Program Bonuses

In Illinois, day-for-day credit lets most people serving a determinate prison sentence earn one day off their term for every day they serve, which generally cuts time behind bars roughly in half. The exceptions matter, though. First degree murder and terrorism carry no credit at all, a long list of violent and sexual offenses are capped at 85% of the sentence served, and large-scale drug trafficking is capped at 75%. Which tier applies depends on the offense of conviction and the date it was committed.¹

The Standard Rate and How It Is Calculated

Under 730 ILCS 5/3-6-3, the Illinois Department of Corrections awards one day of sentence credit for each day in prison on a qualifying offense. A six-year sentence at this rate works out to about three years in custody, with the remaining three years offset by accumulated credit.¹

IDOC calculates sentences on a 30-day-per-month basis. The record office at each facility runs the initial calculation at intake and recalculates whenever the sentence structure changes, whether from additional charges, credit revocations, restorations, or court orders. Every calculation is reviewed by two staff before it is finalized.²

The standard rate applies broadly. Burglary, theft, lower-level drug possession, and many other non-violent felonies all qualify. People serving natural life sentences receive no sentence credit of any kind.¹

Offenses That Limit or Eliminate Credit

Illinois tiers credit by offense severity, and the gap between tiers is large. A qualifying non-violent felony means serving half the sentence. First degree murder means serving every day.

No Credit (100%)

Someone convicted of first degree murder or terrorism receives zero sentence credit and must serve the entire sentence imposed. That rule applies to offenses committed on or after June 19, 1998.¹

85% Served

People convicted of the following types of offenses earn no more than 4.5 days of credit per month, which works out to serving roughly 85% of the sentence:

Attempted murder and related offenses: attempt to commit terrorism, attempt to commit first degree murder, solicitation of murder, and solicitation of murder for hire
Predatory criminal sexual assault of a child, aggravated criminal sexual assault, and criminal sexual assault
Aggravated battery of a child, aggravated battery of a senior citizen, and heinous battery
Aggravated kidnapping, aggravated battery with a firearm, and unlawful possession of a firearm by a repeat felony offender

A second group of offenses lands in the 85% tier only when the court finds the conduct caused great bodily harm to a victim: home invasion, armed robbery, aggravated vehicular hijacking, aggravated discharge of a firearm, and armed violence with a category I or II weapon.¹

75% Served

Serious drug-related offenses involving 100 grams or more of a controlled substance are capped at 7.5 days of credit per month, meaning roughly 75% of the sentence served. The tier covers narcotics racketeering, controlled substance trafficking, methamphetamine trafficking, drug-induced homicide, and Class X felony delivery of controlled substances at that weight threshold.¹

Offense Date Can Change the Tier

Each restricted category has its own effective date. The 85% tier for the core violent offenses applies to crimes committed on or after June 19, 1998. Other offenses were added later. Aggravated domestic battery, for example, falls under the restricted rules only when the offense was committed on or after July 23, 2010. An offense committed even one day before the applicable effective date may qualify for a more favorable rate under the rules in place at that time.¹

Earning Extra Credit Through Programs

Day-for-day is not the only way to shorten a sentence. Illinois offers several additional credit categories that stack on top of the base rate.

Program Sentence Credit

Someone engaged full-time in qualifying activities earns one additional day of credit for each day of participation. Qualifying activities include substance abuse treatment, educational and vocational programs, work-release assignments, behavior modification courses, life skills classes, and re-entry planning. For activities that do not meet the full-time threshold, like volunteer work, self-improvement programs, or other work assignments, the rate drops to half a day of credit per day of participation.¹

Educational Achievement Bonuses

Finishing a degree or passing equivalency testing while incarcerated triggers a one-time credit bonus awarded on top of daily program credit:

High school equivalency (GED): 90 days
Associate degree: 120 days
Bachelor’s degree: 180 days
Master’s or professional degree: 180 days

Supplemental Credit from the Director

The IDOC Director can award additional credit for good conduct, service to the institution, and community service. The caps are 180 days for sentences under five years and 365 days for sentences of five years or longer. A person must serve at least 60 days, including jail time, before becoming eligible.¹

Program Credit for Restricted Sentences

Before 2018, people in the 85%, 75%, or 100% tiers were largely shut out of program-based credit. Public Act 100-3, effective January 1, 2018, opened that door, with floors on how far the actual time can drop:

85% tier: time served cannot fall below 85% of the sentence
75% tier: time served cannot fall below 60% of the sentence (gunrunning stays at 75%)
100% tier: no reduction, regardless of programming

Someone in the 75% tier who actively participates in programming could therefore serve as little as 60% of the sentence, a meaningful change from the pre-2018 rules.³

How Credit Can Be Lost

Credit is not permanent once awarded. Any type of credit, including day-for-day, program, supplemental, and educational, can be revoked for disciplinary violations or breaking facility rules.

IDOC can revoke up to 30 cumulative days of credit within any 12-month period on its own authority. If the amount at issue is larger, or if cumulative revocations during a 12-month period go above that threshold, the department must submit its recommendation to the Prisoner Review Board for approval.⁴

A special rule applies near the end of a sentence. When misconduct happens within 60 days of a scheduled release, IDOC can revoke up to 30 days without Prisoner Review Board involvement. Anything beyond 30 days still requires board approval.⁴

Revocations change the projected release date, not the mandatory release date. The mandatory release date moves only when there is an actual absence from IDOC supervision, such as an escape or release on bond.²

Mandatory Supervised Release After Prison

Leaving prison is not the end of the sentence. Every person released on a determinate sentence must serve a period of mandatory supervised release, which functions like parole. The length depends on the felony class:

First degree murder and Class X felonies: 3 years
Class 1 and Class 2 felonies: 2 years
Class 3 and Class 4 felonies: 1 year

MSR carries conditions set by the Prisoner Review Board, including regular reporting and travel restrictions. Violating those conditions can send a person back to prison, and time spent on supervision before the violation does not always count toward the remaining obligation.⁵

This is where total time under state control gets miscalculated. A four-year sentence for a Class 2 felony at the 50% credit rate means roughly two years in prison followed by two years of mandatory supervised release. That is four years total, not two. Day-for-day credit shortens the prison portion. It does not touch the MSR tail.

1
Illinois General Assembly. Illinois Compiled Statutes 730 ILCS 5/3-6-3 – Rules and Regulations for Sentence Credit
2
Illinois Department of Corrections. Administrative Directive 01.07.400 – Sentence Calculation for Individuals in Custody
3
Illinois General Assembly. Illinois Compiled Statutes 730 ILCS 5/3-6-3 – Rules and Regulations for Sentence Credit – Section 4.7
4
Illinois General Assembly. Illinois Administrative Code Title 20 Part 107 – Sentence Credit
5
Illinois General Assembly. Illinois Compiled Statutes 730 ILCS 5 – Unified Code of Corrections – Felony Sentencing Provisions