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The New 10-Year Planning Rule: What Property Owners Need to Know

Tej Chowdhary, Solicitor at Ranjay Solicitors ​
1 April 2026 by
The New 10-Year Planning Rule: What Property Owners Need to Know
Webmentix Technologies Pvt Ltd, Deepak Kumar

The planning landscape has changed significantly for property owners.

From 25 April 2024, the long-standing ability to regularise certain unauthorised residential developments after four years has been significantly restricted, with a new 10-year enforcement period applying to breaches occurring on or after that date.

This change has important implications for anyone who has carried out, or is considering, unauthorised works.

Why This Matters

Previously, some property owners relied on the passage of time to regularise unauthorised residential developments, provided no enforcement action was taken within four years.

That approach is now significantly more risky.

Under the new framework:

  • Local authorities have 10 years to take enforcement action
  • Properties may remain non-compliant for a much longer period
  • Regularising a development through the passage of time is no longer a short-term option

Increased Risk on Unauthorised Conversions

Unauthorised residential conversions, including flat conversions, HMOs, and changes of use, are now exposed to a longer enforcement window.

This creates several risks:

  • Reduced marketability when selling
  • Difficulties obtaining mortgage finance or refinancing
  • Exposure to enforcement notices requiring reversal of works
  • Potential impact on rental income

Property owners should now take greater care to ensure that any works or changes of use are properly authorised.

Transitional Position – A Limited Window

There remains a limited opportunity to rely on the previous position.

If a development was:

  • Substantially completed before 25 April 2024, and
  • Has existed continuously for at least four years

it may still be possible to regularise the use through a Certificate of Lawfulness.

However, this is a fact-sensitive exercise, and clear supporting evidence will be required.

For developments completed after that date, the 10-year rule will apply.

 

What Should Property Owners Do?

Given the change in law, a more cautious and structured approach is now required.

Establish the Timeline

Determine when the works were substantially completed, as this will dictate whether the 4-year or 10-year rule applies.

Gather Evidence

If relying on historic use, evidence such as utility bills, council tax records, tenancy agreements and photographs will be important.

Consider Regularisation Early

Where possible, consider:

  • Applying for a Certificate of Lawfulness, or
  • Seeking retrospective planning permission

Waiting for immunity is now far less attractive.

Review Existing Properties

Where properties have been altered without consent, it is important to assess the risk of enforcement and take steps to regularise the position where appropriate.

A Shift in Approach

The key takeaway is that the planning system is now less forgiving of unauthorised development.

Strategies based on waiting for a short period before regularising a property are no longer reliable. Instead, property owners should prioritise compliance, proper documentation and early advice.

How We Can Help

At Ranjay Solicitors, we advise on:

  • Unauthorised developments and planning breaches
  • Certificates of Lawfulness
  • Retrospective planning applications
  • Planning enforcement disputes

If you are concerned about unauthorised works or need advice on regularising a property, we can provide clear and practical guidance tailored to your circumstances.

Tej Chowdhary, Solicitor at Ranjay Solicitors

(This article is provided for general information only and does not constitute legal advice. For advice tailored to your circumstances, please contact Ranjay Solicitors.)

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