IS91R: The Notice of Immigration Detention Explained

What an IS91R is

The IS91R is the “Notice to Detainee — Reasons for Detention”. You’ll be given this document when you’ve been detained under immigration powers. It sets out:

• the power under which you’re detained,
• the reasons for the decision to detain you, and
• the factors the Home Office says are relevant (for example a risk of absconding or imminent removal).

It is usually issued alongside the IS91 (the detention authority document held by the detaining location).

Why it matters

The IS91R is important because immigration detention must be lawful and justified. The reasons and factors set out on the notice are the Home Office’s stated basis for holding you — and they can be challenged if detention is unlawful, has lasted unreasonably long, or is no longer justified.

Reviewing the IS91R is often the first thing a solicitor does when assessing whether detention can be challenged or whether to apply for bail.

What to do if you (or a relative) receive an IS91R

• Keep the document safe and note the date detention began.
• Get legal advice quickly — through the Detained Duty Advice Scheme (DDAS) or by instructing a solicitor.
• Consider bail — a solicitor can prepare an immigration bail (BAIL401) application.
• Consider whether detention is lawful — including how long it has lasted and whether removal is realistically imminent.

How Abrahams Solicitors can help

We review the IS91R and detention papers, advise on whether detention can be challenged, and act quickly on bail applications and unlawful-detention claims. If someone you know has just been detained, see our emergency immigration help or contact us. We provide advice and representation; we do not guarantee release or any particular outcome.

Frequently asked questions

Is an IS91R the same as a removal decision?

No. It explains the reasons for detention. A removal decision is separate, though the two can be connected.

Can detention be challenged?

Yes — detention must be lawful and justified. The reasons on the IS91R can be tested through a bail application or a legal challenge.

How soon should we act?

As soon as possible — get advice the same day where you can.

Who reviewed this page

Reviewed for legal accuracy by Imran Shah, Director and SRA-regulated solicitor (SRA No. 509359, admitted 2012), for Abrahams Solicitors — an SRA-regulated firm (firm No. 809071). This page is general information about UK immigration procedure and is not a substitute for tailored legal advice.