Proving the five hectare test for agricultural rights

The five hectare agricultural unit test in Part 6 of Schedule 2 to the General Permitted Development Order 2015 turns on occupation, not ownership, and on the unit as a whole rather than the field you are building in. If the land you occupy for agriculture adds up to five hectares or more, Class A is available. Between 0.4 and five hectares you are in Class B, which is far narrower and does not allow a new building at all. Below 0.4 hectares there are no agricultural permitted development rights.

Councils test that arithmetic more carefully than they used to, because the rights are valuable and the definition is easy to stretch. Getting the evidence together before you build is a great deal cheaper than assembling it during an enforcement investigation.

What an agricultural unit means here

Part 6 defines an agricultural unit as agricultural land occupied as a unit for the purposes of agriculture, including any dwelling or other building on that land occupied for the purpose of farming the land by the person who occupies the unit.

Three words do the work. Occupied, which is about possession and control rather than the name on the title. As a unit, which means the parcels have to be farmed together as one operation. And agriculture, which takes the definition in section 336 of the Town and Country Planning Act 1990: horticulture, fruit growing, seed growing, dairy farming, breeding and keeping of livestock, grazing land, meadow land, market gardens and nursery grounds, among others.

Two consequences follow. Land you own but have let to somebody else on a farm business tenancy is part of their unit, not yours. And land you rent, licence or hold under a grazing agreement counts towards your unit if you are the occupier farming it. Paddocks used for keeping horses for recreation are not agriculture, which is the point where the question of when horses become a business starts to matter.

Land in a garden or the curtilage of a dwelling is not agricultural land for these purposes. Neither is woodland, which has its own rights under Part 6 Class E for forestry.

Class A and the five hectare threshold

Class A permits development on agricultural units of five hectares or more where it is reasonably necessary for the purposes of agriculture within that unit. The main constraints sit in the conditions and limitations rather than in the class itself:

• the ground area covered by a building erected, extended or altered must not exceed 465 m², counted together with any other building put up under Class A within 90 m in the preceding two years
• no part of the development may be more than 12 m high, reduced to 3 m within 3 km of the perimeter of an aerodrome
• nothing within 25 m of the metalled part of a trunk or classified road
• no building designed for housing livestock or storing slurry or sewage sludge within 400 m of a protected building, with limited exceptions
• no dwelling, and no building or structure for a purpose other than agriculture within the unit

That last point is the one that catches diversification schemes. A steel portal frame put up under Class A and then used for storing plant hire equipment or as a workshop for a separate business is a breach of the condition, and the position for farm diversification into workshops and offices is a separate exercise needing planning permission.

Part 6 also carries a removal condition. Where a building is erected under Class A and the use for agriculture ceases within ten years of substantial completion, and planning permission has not been granted for another use, the building has to be removed and the land restored.

Class B and units between 0.4 and five hectares

Class B applies to units of at least 0.4 hectares and less than five. It allows the extension or alteration of an existing agricultural building, plant and machinery, private ways, hard surfacing and certain waste deposits. It does not permit a new building.

The limits on extensions are tight, including a cap on the increase over the cubic content of the original building, a bar on increasing height, and the same restrictions near roads and protected buildings. Read the current text of Class B before you rely on it, because the wording is prescriptive and the council will read it literally.

Smallholders often assume that adding fields under a short grazing licence lifts them into Class A. It can, provided the occupation is real and the parcels are worked together as one unit. A licence signed the week before the digger arrives, over land you have never worked, is the kind of arrangement that an enforcement officer will test and an inspector will see through.

Evidence that establishes the unit boundary

Gather this in a single file and keep it with the deeds:

1. A plan at a recognisable scale with every parcel outlined and its area in hectares, totalled.
2. Title plans for owned land and copies of tenancies, grazing licences or farm business tenancy agreements for land you occupy under an agreement.
3. Your county parish holding number and the field parcel references used in the Rural Payments service, which tie each parcel to a recorded area.
4. Evidence that the parcels are farmed together: cropping plans, livestock movement records, feed and fertiliser invoices, contractor invoices, grazing rotations.
5. Business evidence: accounts showing agricultural turnover, VAT registration where you are registered, herd or flock numbers.
6. A short dated statement of the unit's composition, signed, kept as a record of the position at the time you carried out the works.

Where the unit includes rented parcels, note the term of each agreement. A unit that only exceeds five hectares for the twelve months of a grazing licence is fragile, and if the agreement ends before the building is finished the rights can fall away mid-project.

Prior approval triggers inside the classes

Permitted development under Part 6 is not the same as no involvement from the council. For significant development you have to apply to the local planning authority for a determination as to whether its prior approval will be required for the siting, design and external appearance of the works. That applies to the erection, extension or alteration of a building, the formation or alteration of a private way, excavations and waste deposits, and certain fish tank works.

The application is short: a written description, a plan showing the site, and the fee set out in the current fee regulations. The authority then has 28 days to tell you whether prior approval is required. If it is, you submit details and wait for a decision before starting. If the authority does not respond in time, the deemed provisions in Part 6 allow the development to proceed in accordance with the details submitted, which is a right worth knowing about and a poor thing to rely on deliberately.

Designated land changes the picture. On article 2(4) land, which includes National Parks, the Broads and certain other areas, Part 6 operates differently and more works need prior approval. Larger livestock buildings can also engage screening under the Environmental Impact Assessment Regulations 2017, a point that comes up on poultry units and the screening question.

What to keep on file for a future purchaser

Buildings put up under permitted development have no decision notice, so the file is the only proof. Keep the determination application and the council's response, the drawings as built, dated photographs during construction, invoices showing when work was substantially completed, and the unit evidence described above.

Illustrative example. A 6.2 hectare holding assembled from 4.1 hectares owned and 2.1 hectares held on a five year farm business tenancy, with a 410 m² general purpose store 60 m from the nearest classified road and 480 m from the nearest protected building. Class A is available, a determination application goes in for siting, design and external appearance, and the file records the tenancy term, the parcel references and the completion date. When the farm sells eight years later, the buyer's solicitor gets a bundle rather than an argument.

A buyer who cannot see that evidence will ask for a lawful development certificate under section 191, and obtaining one retrospectively costs more and sometimes fails. If you need to set out the agricultural justification for a scheme that does need permission, a Planning Statement is the document that carries it, and the area and land quality evidence often sits alongside it.

For a view of which supporting documents a farm scheme is likely to need, enter the holding's postcode on PlanScope.

This is general guidance rather than legal advice. A lawful development certificate is the only formal way to confirm that works are lawful. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.