Form N121 UK: Particulars of Claim (Trespassers) Explained

At a glance

• What it is: Form N121 is the particulars of claim for a possession claim against trespassers, filed together with Form N5 (the claim form).
• When it applies: Only where the occupier never had a tenancy or licence — CPR 55.1(b) expressly excludes claims against a tenant or sub-tenant, whatever the state of their tenancy.
• Naming the defendants: If you don't know who is occupying, CPR 55.3(4) requires the claim to be brought against 'persons unknown' as well as any named defendants.
• Service on 'persons unknown': CPR 55.6 sets a special method — documents fixed to the main door/other visible part of the land plus a copy through the letterbox, or fixed to visible stakes on the land, each in a sealed transparent envelope addressed to 'the occupiers'.
• Notice before the hearing: CPR 55.5(2) — 5 days for residential property, 2 days for other land, far shorter than the 21 days used in ordinary possession claims.
• No defence required: CPR 55.7(1)–(2) — no acknowledgment of service, and rule 15.2's defence requirement doesn't apply.
• Enforcement time limit: a warrant of possession against a trespasser can be issued any time after the order (CPR 83.26(10)), but not more than 3 months after the order without the court's permission (CPR 83.26(11)).
• Criminal offence overlap: squatting in a residential building can also be a criminal offence under section 144 of the Legal Aid, Sentencing and Punishment of Offenders Act 2012 — separate from, and can run alongside, the civil claim.

What Form N121 is

Form N121 is the particulars of claim you file when bringing a possession claim against trespassers in the County Court (or, exceptionally, the High Court). It works alongside Form N5, the standard claim form for possession proceedings — N5 starts the claim, and N121 sets out the detail the court needs to decide it.

The form itself asks for five things, mirroring the requirements in paragraph 2.6 of Practice Direction 55A:

1. Identification of the land the claimant has a right to possess, and confirmation that it is occupied by the defendant(s), who entered or remain there without the claimant's consent or licence.
2. Confirmation that the defendant(s) have never been a tenant or sub-tenant of the land.
3. Whether the land includes residential property.
4. The claimant's interest in the land, or the basis of their right to claim possession.
5. The circumstances in which the land has come to be occupied.

A sixth box lets the claimant state that they don't know the names of all the defendants, and a final section asks the court to order possession and costs, verified by a statement of truth.

Who this form is for — and who it is not for

This form only applies to what CPR 55.1(b) calls "a possession claim against trespassers": a claim for recovery of land occupied only by a person or persons who entered or remained without the consent of the person entitled to possession. Critically, the rule expressly carves out tenants and sub-tenants — the definition "does not include a claim against a tenant or sub-tenant... whether his tenancy has been terminated or not."

That distinction matters in practice. If someone was ever your tenant or licensee — even a tenant whose tenancy has since ended and who is now unlawfully overstaying — this is generally not the form to use; possession claims against former tenants follow a different procedural track under CPR Part 55 (typically Section I, general possession claims, or Section II for accelerated possession of an assured shorthold tenancy). Form N121 and the trespasser procedure are for people who never had permission to be there in the first place: squatters in an empty commercial unit, occupiers of undeveloped land, or people occupying under a licence arrangement so informal or defective it never created a tenancy.

Getting this wrong at the outset — using the trespasser procedure against someone who was actually a tenant — risks the claim being challenged on a technical basis, so it is worth being clear on the history of occupation before you issue.

Suing 'persons unknown'

One of the most useful features of this procedure is that you do not need to know the occupiers' names to bring a claim. CPR 55.3(4) requires that "where, in a possession claim against trespassers, the claimant does not know the name of a person in occupation or possession of the land, the claim must be brought against 'persons unknown' in addition to any named defendants."

Form N121 reflects this directly — paragraph 6 lets the claimant state that they don't know the name(s) of all (or some) of the defendants. This is what makes the procedure workable against squatters who won't identify themselves, or where occupiers come and go.

How service works when you don't know who is there

Serving court documents on someone whose name and identity you don't know needs its own rule, and CPR 55.6 provides it. Where the claim has been issued against 'persons unknown', the claim form, particulars of claim and any witness statements must be served by one of two methods:

• Attaching copies to the main door of the property (or another part of the land where they are clearly visible), and — where practicable — also putting copies through the letterbox in a sealed transparent envelope addressed to "the occupiers"; or
• Placing stakes in the land in clearly visible positions and attaching copies of the documents to each stake, again in a sealed transparent envelope addressed to "the occupiers".

If the court itself is arranging service, paragraph 4.1 of Practice Direction 55A puts the burden on the claimant to supply enough stakes and transparent envelopes for this to happen.

The hearing timetable is much faster

Ordinary possession claims give a defendant real breathing room: under CPR 55.5(3), the hearing date must be at least 28 days from issue, the standard period between issue and hearing is up to 8 weeks, and the defendant must be served at least 21 days before the hearing.

Trespasser claims are different. CPR 55.5(2) requires only:

• 5 days' notice before the hearing where the land is residential property; or
• 2 days' notice where it is other land.

The court can shorten these periods further under CPR 3.1(2)(a), and paragraph 3.2 of Practice Direction 55A specifically flags this as worth considering where the defendant has assaulted or threatened to assault the claimant, staff, or another resident, or has caused or threatened serious damage to the property.

No acknowledgment of service, no defence required

Trespasser claims also strip out procedural steps that apply to most other civil claims. Under CPR 55.7:

• An acknowledgment of service is not required, and Part 10 (which usually governs it) does not apply.
• The defendant need not file a defence — rule 15.2, which would otherwise require one, is disapplied.
• Part 12 (default judgment) does not apply to claims under Part 55 at all.

In practice, this means a trespasser can simply turn up to the hearing (or not) and the court will decide the claim on the evidence presented, most of which — under CPR 55.8(5) — must already have been filed and served with the claim form for trespasser cases, since there is no later window for witness evidence in the way an ordinary claim allows.

Where a criminal offence can run alongside the civil claim

For residential buildings specifically, there is a separate criminal dimension. Section 144 of the Legal Aid, Sentencing and Punishment of Offenders Act 2012 makes it an offence to be in a residential building as a trespasser — having entered as a trespasser, knowing or ought to know that you are a trespasser, and living there or intending to live there. "Residential" for this purpose means a building designed or adapted, before the time of entry, for use as a place to live; the offence does not cover open land, commercial premises, or someone who overstays after a lawful tenancy or licence comes to an end.

Where section 144 applies, the police have power to attend and arrest, which can resolve matters faster than waiting for a court date. But it only bites on residential buildings — a squatted commercial unit or a piece of vacant land still relies on the civil possession claim under CPR Part 55 described here. The two routes are not mutually exclusive: reporting a suspected section 144 offence to the police does not stop you also issuing a possession claim, and in commercial or land cases the civil claim is usually the only route available.

What happens if the trespassers don't leave

A possession order is not self-enforcing. If the trespassers remain after the order, the next step is to apply for a warrant of possession so that county court bailiffs can carry out the eviction. This is governed by CPR 83.26.

Two points from that rule matter specifically for trespasser cases:

• Timing: a warrant of possession against a trespasser may be issued at any time after the date on which possession is ordered to be given (CPR 83.26(10)).
• The 3-month limit: no warrant of possession against a trespasser may be issued after the expiry of 3 months from the date of the order without the permission of the court (CPR 83.26(11)). An application for that permission can usually be made without notice to the other side (CPR 83.26(12)).

If you expect any delay between getting the order and enforcing it — for example while arranging bailiffs — keep the 3-month clock in mind, since missing it adds an extra permission step.

Issuing the claim — fees and where to file

The claim form (N5) and particulars (N121) are issued at the County Court hearing centre serving the address where the land is situated, or can be sent there if issued elsewhere first (CPR 55.3(1)). Court fees for recovery-of-land claims are published in the Civil and Family Court Fees schedule (EX50) and are revised periodically — a change took effect from 13 July 2026. Because these fees move, always check the current EX50 schedule on GOV.UK before you issue, rather than relying on a figure quoted elsewhere.

Practical steps if you're dealing with trespassers

1. Confirm the occupiers were never your tenants or licensees. If they were, this is the wrong procedure — a different possession route under CPR Part 55 applies instead.
2. Establish your interest in the land. Form N121 requires you to state your interest or the basis of your right to possession — have your title documents or lease ready.
3. Identify who you can name, and use 'persons unknown' for the rest. CPR 55.3(4) lets you proceed even without full names.
4. Prepare for the special service method if names are unknown. You will likely need to fix documents to the property or use stakes with transparent envelopes, per CPR 55.6.
5. Gather your evidence early. Because trespasser claims skip the usual later evidence stage, your witness statements need to be ready to file with the claim form itself.
6. Check the current court fee on GOV.UK before issuing, since fees are revised periodically.
7. If an order is made and not complied with, apply for a warrant of possession promptly — and be aware of the 3-month permission cut-off under CPR 83.26(11).
8. Consider whether section 144 LASPO 2012 also applies, if the land is a residential building, and whether a police report is a useful parallel step.
9. Take advice early if the situation is contested, urgent, or involves any risk of violence or serious damage — the shortened timetable in trespasser cases can move quickly once issued.

This guide provides general information about Form N121 and possession claims against trespassers in England and Wales. It is not legal advice and is not a substitute for advice tailored to your specific circumstances. The rules described were accurate as at July 2026 and are subject to change — always check the Civil Procedure Rules on justice.gov.uk and the relevant forms on GOV.UK for the current position.

Last reviewed: July 2026 by a non-practising solicitor · Next review due: July 2027 or on rule change.