Serving a Prison Sentence in Spain: What 1/4, 1/2, 2/3 and 3/4 Unlock

Few questions come up as often in sentence enforcement as this one: when will they get out? The answer is not a single date but a calendar of milestones: one quarter, one half, two thirds and three quarters of the sentence each unlock different institutions — leave permits, third grade (open regime), parole. In this guide we explain what can be applied for at each fraction under Articles 36, 90 and 91 of the Spanish Criminal Code (CP) and prison legislation, and we apply it to two fully worked examples: a 4-year sentence and a 9-year sentence. As lawyers regularly acting in penitentiary law, we stress the golden rule from the outset: reaching a fraction never grants anything automatically; it is only the time requirement, to which all the others are added.

How the sentence is computed: the basis of the calculation

Before talking about fractions, the basis must be fixed. The starting point is the official sentence computation (liquidación de condena) approved by the sentencing court, which runs from the actual date of deprivation of liberty: under Article 58 CP, time spent in pre-trial detention in the case is credited in full towards the sentence, unless it coincided with deprivation of liberty already credited in another case — the same period is never credited twice. The four key dates (1/4, 1/2, 2/3 and 3/4) and the final release date are projected onto that basis.

Two important caveats. First: where there are several sentences, the outcome can change completely depending on whether they are served successively, merged or legally accumulated; moreover, in the cases of Article 78 CP the court may order that benefits, leave permits, third grade and parole be computed on the total of the sentences imposed rather than on the maximum term to be served. We explain this in our guide on the accumulation of sentences. Second: the current Criminal Code contains no automatic remission of sentence for work, so the fractions are calculated on the full sentence imposed.

At one quarter (1/4): the first ordinary leave permits

The first relevant milestone arrives once a quarter of the sentence has been served. From that point, Spanish prison legislation (the General Penitentiary Act and its Regulation) allows the inmate to apply for ordinary leave permits (permisos ordinarios) of up to seven days each, subject to annual caps of thirty-six days for inmates classified in second grade and forty-eight days for those in third grade.

The fraction, however, is only one of three general requirements: the inmate must be classified in second or third grade (first-grade inmates have no access to ordinary leave) and must not have displayed bad conduct. Even where all three are met, leave is not an automatic right: the Technical Team reports, the Treatment Board examines the application and, depending on the case, authorisation by the Prison Supervision Judge (Juez de Vigilancia Penitenciaria) is required. In practice, the assessment covers family and social ties, progress in treatment, how far away the release dates still are, and the risk of absconding or reoffending. A refusal based on these factors can be appealed, and preparing the file properly — documenting ties, family support and a release plan — often makes the difference.

At the halfway point (1/2): third grade and advancements

A widespread misunderstanding needs correcting: the Criminal Code sets no general minimum fraction for third grade, which is a matter of prison classification and can even be granted initially. The halfway point becomes decisive where the security period of Article 36.2 CP applies: if the prison sentence imposed exceeds five years, the court may order that classification in third grade not take place until half of the sentence has been served. For certain offences that period is mandatory where the sentence exceeds five years: terrorism, offences committed within a criminal organisation or group, and certain sexual and trafficking offences against minors or especially vulnerable victims.

Where the security period is discretionary, Article 36.3 CP allows the Prison Supervision Judge — on a favourable individual prognosis of social reintegration, after hearing the Public Prosecutor and the Prison Administration — to order the application of the general serving regime, removing that time bar. Aside from the security period, access to third grade requires favourable progress in treatment and a genuine effort to satisfy civil liability, under Article 72 of Organic Law 1/1979, the General Penitentiary Act, to which Article 90 CP itself refers.

The halfway point has two further readings in Article 90 CP: it is the point from which the qualified advancement of parole is computed (up to ninety days per year actually served, as we will see) and the threshold of the exceptional regime for first-time offenders: a person serving their first prison sentence, where it does not exceed three years, may obtain parole at the halfway point (Art. 90.3 CP), except for offences against sexual freedom.

At two thirds (2/3): early parole

Article 90.2 CP allows the court to suspend the remainder of the sentence and grant early parole to an inmate who has served two thirds of the sentence, is in third grade, has displayed good conduct and, while serving the sentence, has carried out work, cultural or occupational activities, either continuously or with results showing a relevant and favourable change in the personal circumstances connected to their previous criminal activity.

On top of this modality sits the qualified advancement: on a proposal from the Prison Administration and after hearing the Prosecutor and the other parties, the Prison Supervision Judge may bring the two-thirds date forward, once half of the sentence has been served, by up to ninety days for each year actually served. It requires continuous activities and effective, favourable participation in victim-reparation or treatment/detoxification programmes. Important: under Article 90.8 CP, these early modalities do not apply to persons convicted of terrorism offences or offences committed within criminal organisations.

At three quarters (3/4): ordinary parole

Three quarters of the sentence is the threshold for ordinary parole under Article 90.1 CP, which sets three requirements: being classified in third grade, having served three quarters of the sentence and having displayed good conduct. The Prison Supervision Judge also weighs the offender's personality, criminal record, the circumstances of the offence, conduct in prison and family and social circumstances, and will not grant the suspension if civil liability has not been satisfied under the criteria of Article 72(5) and (6) of the General Penitentiary Act.

Parole today is a modality of suspending the remainder of the sentence, with a suspension period of two to five years, never shorter than the part of the sentence still outstanding. And it comes with a crucial warning in Article 90.6 CP: if parole is revoked, the time spent on parole does not count as time served. Article 91 CP adds a humanitarian regime that dispenses with the fractions for inmates aged seventy or over and for seriously ill inmates with incurable conditions. We cover the details in our guide on parole requirements.

Example 1: a 4-year sentence

An offender enters prison on 1 January 2026 to serve a single 4-year sentence (48 months), with no additional credits:

Milestone	Time served	Date	What it unlocks
1/4	12 months	1 Jan 2027	Ordinary leave permits (with second grade and good conduct)
1/2	24 months	1 Jan 2028	Start of the qualified-advancement computation
2/3	32 months	1 Sep 2028	Early parole (Art. 90.2 CP)
3/4	36 months	1 Jan 2029	Ordinary parole (Art. 90.1 CP)
Total	48 months	1 Jan 2030	Final release

Since the sentence does not exceed five years, no security period is possible: third grade depends solely on classification, with no minimum fraction. The Article 90.3 CP regime (halfway point for first-time offenders) does not apply, because the sentence exceeds three years. With good progress, a realistic itinerary would be: leave permits from January 2027, progression to third grade when the Treatment Board proposes it, and parole between September 2028 (early) and January 2029 (ordinary).

Example 2: a 9-year sentence

An offender enters prison on 1 January 2026 with a single 9-year sentence (108 months):

Milestone	Time served	Date	What it unlocks
1/4	27 months	1 Apr 2028	Ordinary leave permits (with second grade and good conduct)
1/2	54 months	1 Jul 2030	Third grade if the security period applies; qualified-advancement computation
2/3	72 months	1 Jan 2032	Early parole (Art. 90.2 CP)
3/4	81 months	1 Oct 2032	Ordinary parole (Art. 90.1 CP)
Total	108 months	1 Jan 2035	Final release

Here the sentence exceeds five years, so the court could have imposed the Article 36.2 CP security period: in that case, third grade could not be granted before 1 July 2030, although if the offence is not on the mandatory list the Prison Supervision Judge could restore the general regime (Art. 36.3 CP) and unlock it earlier. If it was not imposed, third grade again depends only on classification. Leave permits, by contrast, do not wait for the halfway point: the file can be worked on from April 2028. And if the inmate keeps up continuous activities and takes part in reparation or treatment programmes, the qualified advancement could bring the early-parole date forward by up to ninety days for each year actually served.

Practical warnings before doing the maths

• The dates are thresholds, not rights: classification, conduct, prognosis and civil liability are added to each fraction.
• Check the official computation: pre-trial detention credits (Art. 58 CP) and calculation errors are caught by reviewing the liquidación de condena and, where appropriate, challenging it.
• Multiple cases change the map: sentence merger, legal accumulation and the Article 78 CP regime can shift every date above.
• Special regimes apart: reviewable permanent imprisonment and terrorism or criminal-organisation offences carry their own, stricter time limits (Arts. 36, 78 and 90.8 CP).

At Alonso Sala Abogados we calculate each client's serving calendar, prepare the files for leave permits, progression to third grade and parole, and appeal refusals before the Prison Supervision Judge. We work to ensure every milestone is applied for at the earliest legally possible moment, with the best-documented file.