Guide Unilateral undertakings, section 106 agreements, habitat mitigation and affordable housing contributions

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3. Guidance

A planning obligation is a legally binding agreement secured under section 106 of the Town and Country Planning Act 1990 as amended. These agreements are regularly referred to as planning agreements or section 106 agreements.

They require a developer or landowner to undertake certain works, or to contribute financially towards the provision of measures to mitigate the negative impacts of their development.

Where planning obligations are required, a planning agreement, drafted by our legal services team and entered into by us and the developer or landowner will usually be appropriate. These agreements will require either financial contributions towards the delivery of infrastructure and/or require the on-site delivery of infrastructure within the proposed development. Due to the administrative burden of monitoring compliance with these requirements monitoring charges will also be required to be paid prior to completion of the agreement. The monitoring charges are set out below:

Scale of development

Charge per financial obligation

Charge per non-financial obligation

Major developments (>10 dwellings)



Minor developments (<10 dwellings)



There will be occasions where the use of unilateral undertakings can assist in ensuring that planning permissions are granted speedily, which benefits both the applicant and us.

A unilateral undertaking is a simplified version of a planning agreement and is only entered into by the landowner. It will only be appropriate in certain circumstances.

We would only normally consider a unilateral undertaking to be appropriate if all the following conditions are met:

  • The person entering into the undertaking is the owner of the land (not merely a purchaser with a conditional contract) and there are no leases or tenancies. If the land is subject to a mortgage/legal charge, mortgage and mortgagee details should be included (see template).
  • The planning obligation will consist solely of the payment of financial contributions, of one or more of the types described in the template, to be paid on the start of development or the date hereof (so, the date the agreement is signed).
  • The undertaking includes an obligation to pay our costs in assessing the adequacy of the undertaking (which will include checking the title to the land) and registering the Undertaking as a local land charge. The current basis of charges is £50. This charge is, however, subject to review and actual costs will be assessed by reference to the rates operating on the date of completion of the agreement. If planning permission is not granted, then the local land charge will be removed.

If any of the above conditions are not met, we will normally consider the matter unsuitable for a unilateral undertaking and will expect the applicant to enter into a conventional negotiated section 106 agreement, which will be drafted by our legal services team under their normal terms of business.

If the applicant considers that the above conditions are met, they submit their planning application with a completed Unilateral Undertaking, together with a plan of the application land and proof of title to the land.

Upon receipt of the draft undertaking, we will assess it and confirm whether it is acceptable or whether amendments are required. We will also check the proof of title submitted. If any amendments are required, the draft will be returned to the applicant.

We are committed to delivering a development management service that meets or exceeds national targets. However, a unilateral undertaking must be completed and signed before the application can be registered and considered. Applicants are therefore strongly advised to allow sufficient time for their draft undertaking to be assessed and, if necessary, amended.

A unilateral undertaking is a legally binding document with significant financial consequences. If you're in any doubt about the meaning and effect of the undertaking you should seek independent legal advice.

We are committed to offering pre-application advice. Where it is intended to submit a unilateral undertaking, you are advised to include this element in your pre-application discussions, so that the details and level of contribution can be agreed before to the submission of a planning application.