Development: what counts as development in planning?

What counts as development is the first planning question to answer. If the works or use are not development, planning permission is not required. If they are development, permission is required — but it may already be granted by the General Permitted Development Order rather than needing a planning application.

In broad terms, development means carrying out building, engineering, mining or other operations, or making a material change of use of land or buildings. Planning law also identifies activities which are specifically treated as not being development.

This distinction matters. Saying that something is permitted development is not the same as saying that it is not development: permitted development is development for which planning permission has already been granted by a development order.

What counts as development?

Section 55 of the Town and Country Planning Act 1990 defines development as building, engineering, mining or other operations in, on, over or under land, or the making of a material change in the use of buildings or other land.

Building operations include demolition, rebuilding, structural alterations or additions and other operations normally undertaken by a builder. Section 55 also specifically provides that changing a building from use as a single dwellinghouse to use as two or more separate dwellinghouses is a material change of use.

If an operation or material change of use is development, it needs planning permission. The next question is whether that permission already exists — for example through the GPDO — or whether an application is required.

What does not count as development?

Section 55 also identifies operations and uses which are not treated as development. Important examples include:

• maintenance, improvement or alteration works which affect only the interior of a building or do not materially affect its external appearance
• changes between uses falling within the same use class, subject to the provisions and exclusions in the Use Classes Order
• use of buildings or land within the curtilage of a dwellinghouse for purposes incidental to the enjoyment of that dwellinghouse
• use of land for agriculture or forestry, including use for those purposes of a building occupied together with the land

There are qualifications. For example, prescribed internal works which increase the floorspace of a building used for retail sale by more than 200 m² are treated as development. Also, the incidental-use exemption concerns the use of land or buildings; it does not automatically exempt any building operations needed to create them.

If something is genuinely not development, no planning permission is needed for that reason. Other regimes — such as listed building consent, Building Regulations, highways controls or restrictive covenants — may still apply.

How can I prove something is not development?

Where the answer matters for a purchase, sale, enforcement issue or proposed project, informal advice is not the same as a binding decision. A certificate of lawfulness can provide formal confirmation where the statutory tests are satisfied.

For proposed works or uses, a certificate can establish that what is proposed would be lawful. For an existing use or operation, the evidence and the relevant enforcement history may also matter. Our planning enforcement section explains the current time-limit regime.

If it is development, do I need a planning application?

If the proposal is development, planning permission can be obtained in different ways. The familiar route is an express planning application, but permission can also be granted by a development order.

The General Permitted Development Order grants planning permission nationally for specified categories of development, subject to the limitations, conditions and any prior-approval requirements of the relevant class. Local development orders and neighbourhood development orders can also grant planning permission in defined circumstances.

The current GPDO dates from 2015 but has been amended many times since. Do not rely on the original 2015 text in isolation. Our GPDO pages are organised around the individual Parts and Classes so you can check the current route relevant to your proposal.

Page Updated: 2nd September 2026

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