The Prison Re-offending Statistics publication provides information on the level of recorded re-offending by individuals released from custodial or Fine Sentence sanctions with the Irish Prison Service. The re-offending rates are calculated as the percentage of individuals who have been convicted of any crime incident during the reference period after their release. This publication primarily provides re-offending estimates of individuals who were released from custody in 2015 (3-year re-offending). In addition, more timely estimates for individuals released in 2018 (1-year re-offending) are provided. For the 3-year re-offending estimates, a period of 3 years with a further 2 years for conviction after release is used to measure a re-offending incident and for the statistics on 1-year re-offending, a period of 1 year after release with a further year for conviction is used as the re-offending period. In addition to updates to existing re-offending estimates, this publication also provides new estimates that show the length of time re-offenders spent in custody prior to release and the type of sanction individuals that re-offended received for their re-offending (Tables 4.5 and 4.6 in chapter "Details of 1-year Custodial Re-offending") .

Historically, CSO estimates of re-offending have excluded re-offending court convictions linked to Road and Traffic incidents (RTI’s) which corresponded to equivalent offences managed by the Fixed Notice Act (Penalty points system). In an update to the prison re-offending series and to provide more comprehensive analysis, court convicted offences from incidents relating to RTI’s have now been included as a re-offending indicator to estimate prison re-offending rates for this publication. The change means the re-offending statistics now include individuals that have received a conviction for re-offending incidents which include RTI related offences. RTI's that are solely managed via the penalty points system without a court conviction continue to be excluded as a re-offending indicator.  A historical comparison and a more detailed analysis of the adjustment to prison re-offending rates is available in the section on Methodological Updates.

Individuals released in 2015 experienced a re-offending rate of 61.7% (they re-offended within 3 years of release and have secured a court conviction within another 2 years). This is a slight increase on the equivalent rate for 2014 (60%) but remains a marked reduction on the re-offending levels for individuals released in 2011, where over two-thirds (67.8%) of individuals re-offended.