How sentence milestones are calculated in the Spanish system
Once a prison sentence becomes final, the sentencing court approves the sentence computation (liquidación de condena): a document that sets the date on which the sentence starts to run, credits time already served and projects the dates on which the relevant fractions are reached. Those fractions — one quarter, one half, two thirds and three quarters — are not arithmetic curiosities: each one opens the door to a different prison-law institution. This calculator reproduces that arithmetic on an indicative basis, computing date-to-date and crediting pre-trial detention.
The starting point is the credit for pre-trial detention. Article 58 of the Spanish Criminal Code orders that time spent provisionally deprived of liberty be credited in full against the sentence imposed in the same case, and allows it to be credited in a different case once it is verified that it has not been credited elsewhere: the same period is never counted twice. In practice, every day of pre-trial detention brings the entire prison calendar forward by one day, including the final release date.
One quarter: ordinary prison leave
The first milestone arrives at one quarter of the sentence. From that date, article 47.2 of the Prison Act (LOGP) and article 154 of the Prison Regulation allow the inmate to apply for ordinary prison leave, conceived as preparation for life in freedom. The time fraction is only one of three requirements: the inmate must also be classified in the second degree of treatment (or the third) and show good conduct. The indicative maximum is 36 days of leave per year for inmates in the second degree and 48 days for those classified in the third degree.
Who decides on the leave
Reaching the date grants nothing by itself. The prison's Treatment Board examines each application, weighing risk variables (absconding, reoffending, family and social ties) and, depending on the length of the leave and the degree, the grant requires authorisation from the prison supervision judge. Refusals can be appealed, and legal assistance makes a real difference at that stage.
One half: security period and exceptional conditional release
The halfway point concentrates two institutions that should not be confused. The first is the security period of article 36.2 of the Criminal Code: where the prison sentence imposed exceeds five years, the sentencing court may order in the judgment that classification in the third degree (open regime) not take place until half the sentence has been served. It is not automatic: under the general rule it depends on the judgment expressly imposing it. However, for the offenses listed in article 36.2 itself — including, among others, offenses committed within criminal organisations or groups and certain serious offenses against child victims — that security period is mandatory whenever the sentence exceeds five years.
The second institution is the exceptional conditional release of article 90.3 of the Criminal Code: those serving their first prison sentence, where it does not exceed three years, may obtain conditional release once half is served, if they meet the remaining requirements of article 90 (third degree, good conduct, accredited activities). The provision itself excludes those convicted of offenses against sexual freedom from this route.
Two thirds: early conditional release
Once two thirds are served, article 90.2 of the Criminal Code allows the prison supervision judge to grant early conditional release to those who have carried out work, cultural or occupational activities on a continuous basis or with relevant results, provided they satisfy the other requirements of article 90.1 except the three-quarters threshold. The same provision contemplates an additional advance: once half the sentence is extinguished, and on a proposal from the prison administration, the two-thirds date may be brought forward by up to 90 days for every year actually served, provided the person also demonstrates effective and favourable participation in victim-reparation or treatment programmes.
Three quarters: ordinary conditional release
The general regime of article 90.1 of the Criminal Code demands three requirements for ordinary conditional release: classification in the third degree, having served three quarters of the sentence and good conduct. The prison supervision judge also weighs the person's character, record, the circumstances of the offense, conduct while serving the sentence and family and social circumstances, and will not grant the suspension if civil liability has not been satisfied in the legally established terms.
One change of model deserves emphasis: since the 2015 reform, conditional release is a form of suspension of the remainder of the sentence. The practical consequence is severe: if the suspension is revoked, the time spent on conditional release does not count as time served, and the person returns to prison to serve the entire portion that was pending on release.
Final release (licenciamiento definitivo)
The calendar closes with the final release: the date on which the sentence is fully extinguished and all prison-law subjection ends, including any conditional release in progress. It is approved by the sentencing court on a proposal from the prison, in accordance with the computation. From that date, moreover, the periods for expunging the criminal record begin to run.
What arithmetic does not decide
These dates are necessary time conditions, never sufficient ones. Degree classification depends on the Treatment Board and the prison administration; leave and conditional release, on the prison supervision judge; and everything rests on conduct reports, reintegration prognoses and the satisfaction of civil liability. In addition, where there are several sentences, legal accumulation under article 76 of the Criminal Code sets maximum terms, and article 78 allows prison benefits, leave, the third degree and conditional release to be computed over the total of the sentences imposed rather than over the resulting maximum: in those scenarios the real calendar can differ substantially from the one this tool produces. A technical review of the computation — and of the possibility of accumulating scattered sentences — is often the most valuable step of the whole enforcement stage.