In this Q&A we explore just how easy it is to change your development once planning permission is granted, as well as the pitfalls to watch out for.

I have secured planning permission but want to make some changes to the scheme. What are my options?

There are a number of options. Which is most appropriate will depend on the nature and scale of the changes:

• For non-material amendments, changes can be made to the existing planning permission using section 96A of the Town and Country Planning Act 1990.

• For more significant changes you can apply to “vary” the conditions on a planning permission using section 73 of the Act.

• Where changes are too significant to be accommodated by way of a section 73 permission, you can secure a new permission either for the whole site, or part of it. Where you secure a new permission for part only of the site, to be delivered alongside the original permission on the remainder, this is often referred to as a “drop-in” permission, although this term has no legal status.

If you need longer to implement your planning permission, or to secure reserved matters approval, you must secure a new permission, as neither section 96A, nor section 73 applications can be used to extend an implementation period.

What is meant by a “non-material amendment”?

There is no statutory definition of a non-material amendment. Instead the local planning authority must determine, on the specific facts of each development, whether changes proposed are material.

They should do this taking into account all previous non-material amendments to that permission, to avoid applicants seeking to circumvent these restrictions by making lots of small amendments, which add up to be a material change.

Consequently, there is lots of variation between the scale of changes which can be made using this route. If you disagree on whether a specific change is material, it is very difficult to challenge this.

If you can agree that a specific change is non-material, then the change to the planning permission can be made using a slimmed-down process: there is no statutory requirement for consultation and the determination period is only 28 days.

On the other hand, only someone with an interest in the land can make the application.

How does this differ from a section 73 application?

There are some crucial differences:

• The scale of changes that can be made via a section 73 application is much greater. As a result of government guidance, these applications have often been referred to as minor material amendments. However, in the recent case of Armstrong v Secretary of State for Levelling-Up, Housing and Communities [2023] EWHC 176 (Admin); [2023] PLSCS 21 it was held that this classification doesn’t accurately reflect the law and there is no limit on the scale of changes which can be made using this route, provided the development permitted by the conditions is consistent with the description of development.

• Section 73 permissions can only change conditions. Section 96A applications, on the other hand, can be used to change any part of the planning permission, including the description of development, and to add new conditions. Case law confirms that a section 73 permission cannot do this.

When taken together with the fact that a section 73 permission cannot permit different forms of development in the conditions and the description of development, this does mean that care must be taken when considering the implications of changes proposed via a section 73 application.

For example, changing the number of units within a scheme is fine, provided the description of development is silent on this. However, where the description specifies this detail, a section 73 permission cannot permit a different number.

This issue is sometimes addressed by using a combination of section 96A and section 73 applications.

The first removes the details to be changed, or moves it to a condition, and the second application makes the substantive alteration.

• A section 73 application results in a new planning permission. This gives you a choice on which scheme to develop, as you can stick with the original consent. This differs from a section 96A approval, which amends the original permission, and where you must be certain about the changes before applying for them.

• As a section 73 application results in a new permission, the application process, including determination timetable, is generally the same as for a full planning permission. The information requirements tend to be far greater than for a section 96A application, and can include full updates to documents, such as environmental statements, in some cases.

It’s also worth noting that, as a section 73 application results in a new permission, it should be decided based on the policy and factual position at the time the section 73 application is determined.

This can cause problems where there have been significant changes – for example in the amount of affordable housing required – unless there are clear transitionary provisions to deal with section 73 applications.

If I want a drop-in permission, what do I need to consider?

Drop-in permissions give you even greater flexibility than section 73 permissions in terms of the type of changes which can be made. However, they can pose significant risks if not handled carefully.

At the Court of Appeal, the case of Hillside Parks Ltd v Snowdonia National Park Authority [2022] UKSC 30; [2023] EGLR 4 raised some questions about the use of drop-ins, although the Supreme Court has helpfully clarified matters slightly.

The position is now that, if you implement a first planning permission, then implement a second planning permission which overlaps with the first, you cannot continue to develop pursuant to the first permission unless the element which overlaps is severable from the remainder of the development permitted by the first permission.

There is no guidance on what it means for a planning permission to be severable, and this may vary depending on the details of the permission. If you want a permission to be severable, you should address this head-on with the LPA.

Helpfully, the Supreme Court did confirm that development already carried out pursuant to the first permission would not be rendered unlawful retrospectively by the implementation of a drop-in permission.

Consequently, where the development to be carried out pursuant to the drop-in starts after all other development has been completed, the risk is significantly reduced.

The other critical area to navigate when dealing with drop-in permissions is compatibility with the original permission.

Care is usually taken to ensure that the two schemes are physically compatible – roads align, the design concepts complement each other – but there can be greater difficulty ensuring functional compatibility.

Thought needs to be given to matters such as whether there should be changes to the amount of affordable housing to be delivered by the first permission, how contributions are to be treated, and whether there should be joint strategies, such as travel plans, for the whole scheme, or a separate one for each permission.

These issues are not insurmountable in most cases, but do need careful thought. They also tend to need the support of the LPA, which may be nervous about granting a drop-in without clarity on the implications for the original permission.

Since the Supreme Court decision there has been an appeal decision where it was considered appropriate to refuse a drop-in application because of the impact it could have on deliverability of the original permission.

If the LPA doesn’t support a drop-in, what are the alternatives?

There is always the option to submit a fresh planning permission for the whole site, including those parts that have already been developed.

Indeed, based on the judgment in Hillside, many LPAs are favouring this. However, while this may work on some developments, for more complex schemes this approach poses problems, such as changes in policy and law, as well as the potential cost implications of submitting an entirely new application, with all supporting reports.

What else should I bear in mind?

The position around the community infrastructure levy for either revised or new planning permissions can be complex, especially if there have been different charging schedules during the evolution of the scheme.

There will also be different requirements around biodiversity net gain depending on whether a permission is a variation or a fresh consent. These implications should be considered when determining the most appropriate strategy.

As you can see, there are many ways to update a planning permission. Each has its own pitfalls and opportunities, so care should be taken when deciding on your strategy for evolving consents.