Last reviewed: July 2026
UK Prison Categories Explained: A, B, C and D
Categorisation is one of the most important but least understood parts of the prison system. It is not a punishment in itself – it is a security and risk-management tool, reassessed regularly, that determines where someone can safely be held and what kind of regime they experience.
The four categories at a glance
| Category | Who it’s for | Typical regime |
|---|---|---|
| A | Prisoners whose escape would be highly dangerous to the public or state security | Maximum security, held in 8 high-security “dispersal” prisons |
| B | Prisoners who don’t need maximum security, but escape must be very difficult | Local and training prisons, higher security than C |
| C | Prisoners who can’t be trusted in open conditions but are unlikely to try to escape | Training and resettlement prisons; holds the largest share of the population |
| D | Prisoners who can be trusted in open conditions | Open prisons, minimal perimeter security, ROTL eligibility |
How categorisation decisions are made
When someone is first sentenced, the court and prison service assess a range of factors: the seriousness of the offence, any history of violence or escape attempts, links to organised crime or terrorism, and the risk to the public if the person were to escape. Category is reviewed at regular intervals throughout a sentence – typically annually, though this varies – and most prisoners who behave well and engage with their sentence plan move down through the categories as their release date approaches, sometimes ending their sentence in open (Category D) conditions.
Why category matters for families
Category affects almost everything practical about a sentence: which prison someone is allocated to (and therefore how far family need to travel for visits), how much time is spent out of cell, what work and education is available, and how close someone might be to release on temporary licence. A downgrade in category is often, though not always, a sign that things are progressing well.
Read the detail for each category
We have a dedicated, in-depth guide for each category:
- Category A prisons – the eight high-security dispersal sites
- Category B prisons – local and training prisons
- Category C prisons – training and resettlement, the largest category
- Category D (open) prisons – minimal security, ROTL eligible
- Assuming category is fixed for the whole sentence – it is reviewed regularly and most people move down over time.
- Assuming a “worse” category means a longer sentence – category reflects risk and escape potential, not the length of the sentence itself.
- Thinking women are categorised the same way as men – the female estate uses a closed/open system, not A-D.
- Assuming all prisoners at a high-security site are Category A – dispersal prisons hold a mix of Category A and B prisoners.
Can a prisoner request a category review?
Yes, though reviews are also scheduled automatically at set intervals. A prisoner (or their solicitor) can ask for an earlier review if there has been a significant change in circumstances.
What happens if someone is upgraded to a higher category?
This can happen after a serious incident, adjudication, or new information about risk, and it usually means a transfer to a more secure establishment with a stricter regime.
Is Category D the same as being released?
No. Category D (open) prisoners are still serving their sentence and still in custody, but with much lower security and, often, opportunities for supervised work or home visits in the community as part of resettlement.
Does moving to a lower category guarantee a transfer straight away?
No. A category downgrade means someone is eligible to move, but an actual transfer depends on space being available at a suitable prison, which can sometimes mean a wait even after the paperwork is approved.
Where can I find official guidance on categorisation?
See GOV.UK’s guidance on prison security categories and transfers and the Prison Reform Trust for wider advice.
For a starting point across all our guides, see our prison guide hub.
