Phasing conditions and how they work at each scale

A phasing condition on a planning permission does two jobs at once: it sets out which parts of the site are built in which order, and it becomes the reference point for every other condition and obligation that uses the word "phase". Get the phasing plan wrong and you will spend the next five years arguing about what triggers a road, a play area or an affordable housing transfer.

Phasing matters at every scale above a single plot, but what it controls changes as unit numbers rise. On a 15 unit site a phasing condition is usually about construction access and mud on the road. On a 400 unit site it is the mechanism that keeps the scheme solvent.

What a phasing condition is meant to control

The usual drafting requires a phasing plan to be submitted to and approved in writing by the local planning authority before development begins, and then requires development to be carried out in accordance with the approved plan. Attached to that are trigger conditions expressed as "prior to first occupation of Phase 2" or "before Phase 3 begins".

A well drafted condition does four things. It identifies each phase by a numbered area on a plan, not by a description. It states the unit numbers and any non residential floorspace in each phase. It allows phases to be built concurrently or out of sequence with written agreement. And it leaves the detailed construction programme out of the planning condition entirely, because a programme is a commercial document that will change.

One drafting trap. Where a condition requires the whole phasing plan to be approved before any development begins, and the applicant wants to start enabling works, the authority has to agree either a separate enabling works phase or an exclusion for site clearance and remediation. Ask for that at the decision stage rather than six months later.

Drafting a phasing plan that can actually be discharged

Councils refuse phasing plans for predictable reasons. The phase boundaries do not match the boundaries used in the section 106 agreement. The plan shows phases that cannot be accessed independently. Or the plan allocates no land for the drainage, open space or play provision until the last phase, which is exactly the outcome the condition exists to prevent.

Three habits prevent most of that.

1. Draw the phase boundaries once and use the same plan reference in the condition, the section 106 agreement and the discharge submissions.
2. Make each phase independently serviceable, with its own access, drainage outfall and refuse vehicle route. Refuse collection is a recurring failure point as numbers rise.
3. Front load the infrastructure that conditions and obligations tie to occupation. If the primary access, the attenuation basin and the first area of open space all sit in Phase 1, the triggers look after themselves.

Infrastructure trigger points tied to occupations

Occupation triggers are the standard currency. They work because they are easy to monitor and hard to argue about, and they transfer risk to the developer rather than to future residents.

Typical trigger structures on a larger residential scheme:

The transport triggers deserve particular attention because they are often set by the highway authority's modelling rather than by the planning officer. Where a Transport Assessment identifies a junction improvement needed at a particular level of occupation, that number becomes the trigger, so the modelling assumptions are worth challenging before the figure is written into a condition.

A practical point about planting. Landscape conditions tied to "first planting season following occupation" can leave a phase with bare verges for eleven months. Ask instead for planting within the first available season following practical completion of the phase, which usually gives a better result on site and is easier to monitor.

Effect of implementing one phase on the whole permission

Here is where phasing interacts with the life of the permission, and where the answer differs between a full and an outline consent.

On a full planning permission, a single material operation carried out lawfully anywhere on the site implements the whole permission, and the three year time limit under section 91 of the Town and Country Planning Act 1990 is satisfied for all of it. That is why developers on large full permissions often carry out an early material operation. The permission then remains alive indefinitely, subject to any condition requiring the development to be carried out in accordance with an approved phasing plan.

On an outline permission, each phase can have its own reserved matters approval, and the usual drafting allows reserved matters for later phases to be submitted beyond the standard three years where the condition expressly permits it. Without that wording, the whole scheme has to secure reserved matters approval within the stated period. The decision between the two routes drives a good deal of later flexibility, which we set out in choosing between an outline and a full application.

A lawful implementation also has to be a genuine material operation under section 56 of the 1990 Act, carried out in compliance with any condition that had to be satisfied first. An operation carried out in breach of a pre start condition may not implement the permission at all, which is a bad discovery to make in year four.

Levy liability and relief across phases

Phasing changes how the Community Infrastructure Levy bites. Under the Community Infrastructure Levy Regulations 2010 as amended, each phase of a phased planning permission is a separate chargeable development, with its own liability, its own start date and its own payment schedule.

That has four consequences worth planning for.

• Liability crystallises phase by phase rather than in one sum at the start, which helps cash flow considerably on a long scheme.
• The charging schedule and indexation applicable to each phase are those in force when that phase begins, so a later phase can cost more or less per square metre than the first.
• Relief and exemption claims, including social housing relief and self build exemption, are made per phase and must be claimed and approved before that phase begins.
• An outline permission is treated as phased where it is granted subject to a condition requiring phased development. A full permission is only phased for levy purposes where the permission expressly provides for phases, so the phasing condition wording matters.

Smaller schemes have a different concern, namely whether the levy applies at all. The minor development exemption and the treatment of existing floorspace are set out in the 100 square metre minor development exemption.

Check the authority's current charging schedule and indexation figure at the point each phase begins rather than relying on the figure quoted at the decision.

Section 73 amendments to phasing

Phasing almost always changes. The route is an application under section 73 of the 1990 Act to vary the phasing condition, which produces a new permission sitting alongside the original.

Two cautions. A section 73 permission is a new permission, so the obligations in the original section 106 agreement do not automatically attach to it unless the agreement is drafted to bind successor permissions or a deed of variation is completed. And a section 73 cannot be used to change the description of development, so moving units between phases is fine while changing the number of units overall is not.

Where the change is minor, such as redrawing a phase boundary by a few metres, a non material amendment under section 96A may be enough. Authorities differ on where they draw that line, so ask before you choose the application type. Fees differ too, and they are indexed annually, as covered in how planning fees escalate with unit numbers.

Common drafting failures

The recurring ones, in the order they cause the most damage:

• Phase boundaries in the condition that do not match those in the section 106 agreement
• Triggers expressed as dates rather than as events, which become unachievable the moment the programme slips
• A condition requiring all infrastructure before first occupation of Phase 1, with no apportionment
• No mechanism to vary the phasing by written agreement, forcing a section 73 for every change
• Affordable housing trigger expressed by percentage of the whole scheme rather than per phase, so the first phase carries the lot
• Open space transfer triggered on completion rather than occupation, leaving a management gap

On affordable housing, set out the per phase delivery in the Affordable Housing Statement at application stage. It is far easier to agree a schedule before the committee report is written than to renegotiate it after.

Enter your postcode on PlanScope to see which reports a phased residential scheme is likely to need.

This is general guidance rather than legal advice. 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.