Significant infrastructure projects (SIP): changing a project (a variation)

The applicant can apply to change a proposal or add land for compulsory purchase (a variation). This guidance explains how and when we decide on a variation.

Before we decide how to examine the application, the applicant can apply to make a ‘general variation’ to:

• change part of the design or operation of the proposal
• make major changes to the wording of the draft infrastructure consent order

Applications must be made within 14 days of the representation period ending.

If we have already decided on the examination procedure, the applicant can only apply to make a general variation after the first hearing or inquiry opens.

Applications must include:

• a description of the variation and its effects, including revisions proposed to application documents
• justification for the timing and need for the variation, and
• an explanation of how the variation could be examined within statutory timescales

They must also include:

• details of any publicity or consultation, comments received, and how those comments have been taken into account, or
• a statement that no publicity or consultation was done.

The application must be made using the form, including the fee (see our schedule of fees for more information).

Applicants should give us advance notice of any application to make a variation to avoid delaying the examination and processing the fee.

The applicant can request to add more land for compulsory purchase but must first consult with affected landowners for at least 28 days.

The applicant must submit the request within 28 days of the consultation ending and include:

• justification for the acquisition and variation
• reasons why the land was not included initially
• the list of people affected by compulsory purchase (updated ‘book of reference’)
• references linking each person to their representation
• details of anyone who could make a claim if the consent is implemented
• how the acquisition will be funded
• how the variation can be examined within the statutory timescales
• a draft notice meeting the requirements of Compulsory Acquisition regulation 19(2)
• the required fee (see our schedule of fees for more information)

We will publish any advice we provide to the applicant about the proposed variation on our website.

We will decide whether to accept or reject a variation. We will not accept a variation if it results in a substantial change to the project. This will depend on the case. In reaching a view we may consider:

• changes to the core function, scale, layout, or impact of the development
• the extent to which there would be changes to any significant effects (positive or negative, individual or cumulative)
• risk of new significant impacts not considered before
• need for major updates to the environmental statement
• the gravity of any new legal issues, for example in relation to human rights

When deciding whether to accept an application, we consider how it could affect the efficiency and timing of the examination.

We may reject the application if: 

• there are missing required documents
• statutory deadlines cannot be met
• a similar application has already been rejected

We provide reasons in writing if we reject an application.

If we accept an application, we will:

• re-publicise and consult on the varied application (unless there is limited change)
• review the examination procedure and timetable
• update the primary examination notice if necessary
• hold additional hearings or inquiries if needed

If other consultations are programmed (e.g. in relation new evidence) we will consult on the varied scheme at the same time as the other information.

For general variation applications made before the examination procedure is chosen, we decide within 7 days. The applicant must then submit all related documents to us within 28 days (or other deadline we specify).

For general variation applications made after the first hearing or inquiry we will make the decision when it is practical to do so.

For compulsory acquisition variations, we decide within 15 days unless the Welsh Ministers have issued a direction to extend the decision period. 

• The Infrastructure Consent (Pre-Application and Application and Transitional Provisions) (Wales) Regulations 2025
• The Infrastructure Consent (Examination and Decision) (Procedure) (Wales) Regulations 2025
• The Infrastructure Consent (Compulsory Acquisition) (Wales) Regulations 2025