Determined Boundaries in the UK: Form DB Step-by-Step (HM Land Registry PG40 Supplement 5)

What a determined boundary is — and when you need one

HM Land Registry's default rule is the general boundary (Land Registration Act 2002, section 60): the boundary shown on a title plan is a general line, not an exact one.¹ For most properties, this is sufficient. You know roughly where the line runs; physical features (walls, fences, hedges) approximate the legal position.

But for some properties, the general boundary is too imprecise. The most common scenarios in 2026:²

• A development that requires exact coordinates — a planning application, a building regulations submission, or a site layout that needs the boundary in OSGB36 to the nearest centimetre
• A dispute where the parties want the line locked in — a Form DB determination is more enforceable than a Single Joint Expert report
• A sale where the buyer or lender requires certainty — some commercial lenders will not lend on land with a general boundary
• A change of use that requires planning certainty — a barn conversion, a change of use from agricultural to residential

In all of these scenarios, the remedy is a determined boundary application under HM Land Registry Practice Guide 40 Supplement 5 (PG40 Supp 5).³

The 6-step Form DB process

A Form DB application is a structured process with hard rules. Here's what happens at each step.

Step 1: Instruct a RICS-regulated surveyor

The applicant instructs a surveyor regulated by RICS or CICES. The surveyor will:

• Review the documentary baseline (title plan, historic conveyances, any prior boundary agreements)
• Conduct a fresh site visit to identify physical features
• Produce the application plan and the coordinate schedule
• Sign the surveyor certification in Section 4 of Form DB

You cannot submit a Form DB application without a RICS- or CICES-regulated surveyor's certification.

Step 2: Identify every adjoining owner

The applicant (or their solicitor) requests the current register entries for every property that adjoins the application boundary. The adjoining owners are identified by their current registered addresses on the title register.

If any adjoining owner is a company, the current company search must be obtained from Companies House to confirm the registered office address.

If any adjoining owner is deceased, the personal representatives (executors named in the will, or administrators appointed by the Probate Registry) must be identified and served.

The applicant is responsible for getting the list of adjoining owners right. Missing one can invalidate the entire application.

Step 3: Serve Form DB notices on every adjoining owner

A Form DB notice is served on each adjoining owner. The notice includes:

• A copy of the application plan
• A copy of the coordinate schedule
• A statement that the adjoining owner has 15 days to respond
• A response form (consent or objection)

Service is by registered post or recorded delivery to the address on the register. The 15-day clock starts on the date of delivery, not the date of posting.

The applicant must keep proof of service (the recorded delivery receipt) for at least 6 years. If the First-tier Tribunal later reviews the application, the applicant must produce proof of service.

Step 4: Handle the responses

Three possible outcomes from the 15-day window:

All adjoining owners consent in writing. The application proceeds. The determined boundary is registered against the applicant's title and the adjoining owners' titles.

Some adjoining owners consent, others don't respond. Non-response is treated as deemed consent under PG40 Supp 5. The application proceeds as if the non-responding parties had consented. The non-response is noted in the application file.

Any adjoining owner objects in writing. The application is referred to the First-tier Tribunal (Property Chamber) for determination. The Tribunal will hear evidence from both the applicant and the objector (typically through expert surveyors) and issue a binding decision.

Step 5: Submit the Form DB application to HM Land Registry

The application is submitted to HM Land Registry with:

• The completed Form DB (1 page + plan + coordinate schedule)
• All consent letters from adjoining owners (or proof of service if deemed consent)
• The application fee (currently £150-£300 depending on title value)
• The supporting evidence (desktop study notes, site photographs, surveyor certification)

HM Land Registry checks the application for completeness and either accepts it (registers the determined boundary) or returns it with a query.

A typical determined boundary application takes 8-12 weeks from instruction to registration, assuming all adjoining owners consent.⁴

Step 6: Registration and aftercare

Once the determined boundary is registered, the OSGB36 coordinates become the legal line for the applicant's title and all adjoining owners' titles. The determined boundary is binding on the current owners and all future owners.

If a subsequent owner wishes to challenge the determined boundary, the only route is the First-tier Tribunal (with the burden of proof on the challenger). Determined boundaries are treated as conclusive by HM Land Registry and the courts.

The plan requirements (PG40 Supplement 5)

The plan is the most important part of the Form DB application. PG40 Supp 5 sets detailed requirements.³

Scale and format

• Scale: typically 1:500 (residential) or 1:1250 (larger plots)
• North arrow: preferably to OS National Grid true north
• Linear scale bar: in metres
• Sheet size: typically A3 or A1

Required elements

The plan must show:

• The current general boundary in red (line width 0.5mm minimum)
• The proposed determined boundary in green (line width 0.5mm minimum)
• Sufficient Ordnance Survey detail to identify the land: roads, buildings, distinctive features
• Every boundary point labelled with a unique reference (V1, V2, V3, ...)
• A coordinate schedule in OSGB36 (eastings, northings, heights to 3 decimal places) for every boundary point
• Surveyor signature and date, with RICS or CICES membership number
• Applicant signature and date

Accuracy standards

The plan must be produced to RICS Measured Surveys 3rd edition Section 4 deliverable standards, with an accuracy band of A (±15-25mm) or B (±50mm).⁵

In practice, most determined boundary plans are produced to Band A accuracy using total stations or terrestrial laser scanners.

The surveyor certification

PG40 Supp 5 requires the surveyor to certify the following on the plan and in the application:

• Surveyor's full name and RICS / CICES membership number
• Firm name and Professional Indemnity insurance confirmation
• Date of survey and date of plan production
• Methodology statement (instrumentation, accuracy band)
• Statement that the plan is consistent with RICS Measured Surveys 3rd edition Section 4
• Statement that the determined boundary reflects the surveyor's professional opinion based on the evidence examined

The certification carries personal professional liability. If the determined boundary is later found to be incorrect, the surveyor may be sued by any party who relied on it.

Common reasons Form DB applications fail

In 2026, the most common reasons HM Land Registry returns a Form DB application:⁴

1. Incomplete adjoining owner list — missing an owner, or serving to the wrong address (e.g. the owner's old home address, not the address on the current register)
2. Insufficient evidence of service — no recorded delivery receipt, or the receipt doesn't match the address on the register
3. Plan accuracy below PG40 Supp 5 standard — typically a 2D CAD plan without a coordinate schedule, or a coordinate schedule that doesn't match the plan
4. Surveyor not RICS or CICES regulated — or the regulation has lapsed
5. Objection from an adjoining owner — the application is referred to the Tribunal; the applicant must then fund the Tribunal process or withdraw the application

A well-prepared Form DB application has a near-100% acceptance rate on first submission. A poorly prepared one is likely to be returned 2-3 times before acceptance.

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Next steps

If you are considering a determined boundary application:

1. Read the complete boundary survey guide — the foundational 4,000-word pillar article.
2. Book a 15-minute clarity call with an Icelabz surveyor. We'll review your situation and give you a fixed fee for a Form DB application.
3. See our boundary survey service page — including 2026 cost bands for the full application process.

References

Book a 15-minute clarity call with an Icelabz boundary surveyor. We'll review your situation and give you a fixed fee in 24 hours. Or read the complete boundary survey guide and see the boundary survey service page for the full service description.