4 year rule vs 10 year rule - lawful development

Lawful Development Certificates – Conversion of a House into Flats

Under Section 171B of the Town and Country Planning Act 1990, the time limits for enforcement action determine when a development may become lawful through the passage of time.

Historically, the subdivision of a single dwellinghouse into two or more self contained flats could become lawful after 4 years of continuous use. This was because Section 171B(2) previously applied a four year time limit to changes of use to a single dwellinghouse.

However, the law changed following the Levelling Up and Regeneration Act 2023, which came into force on 25 April 2024.

The legislation has introduced a single 10 year enforcement period for all breaches of planning control, including:

• Subdivision of a house into flats
• Changes of use
• Operational development

As a result, creating flats without planning permission now requires 10 years of continuous use before it can become lawful through a Lawful Development Certificate (Existing Use).

For uses that became lawful before 25 April 2024, the previous 4 year rule may still apply depending on the specific circumstances and evidence available.

What Is Considered a Separate Dwellinghouse?

For planning purposes, a unit will generally be considered a separate dwellinghouse if it:

• Forms a self contained planning unit
• Contains the normal facilities for living, cooking and sleeping
• Is occupied by a single person or a group living together as a single household

Where a building is subdivided into separate self contained units, each unit may constitute a separate planning unit.

Burden of Proof in Lawful Development Applications

Applications for a Lawful Development Certificate (LDC) are determined on legal evidence rather than planning merits.

The applicant must demonstrate that the use or development has existed for the required time period on the balance of probability.

This means:

1. The evidence must show it is more likely than not that the use has existed continuously.
2. The stricter criminal standard of proof (beyond reasonable doubt) does not apply.
3. Evidence from the applicant can be accepted without independent corroboration if it is clear, precise and credible.

If the local planning authority has no evidence to contradict the applicant's evidence, and the information provided is sufficiently detailed and consistent, there is generally no reason to refuse a certificate.

Important Note

Establishing lawful use through passage of time can be complex, particularly where:

• the property has been subdivided into flats
• occupation has changed over time
• evidence is incomplete or inconsistent

The most appropriate strategy will depend on the specific facts and available evidence.

If you believe a property may qualify for a Lawful Development Certificate for existing use, contact 4D Planning for professional advice on the best approach.

Example Projects

• House Conversion into residential units in Hackney
• Outbuilding in Redbridge 10 year evidence
• Roof terrace in RBKC 4 years evidence

4D Planning have many more case studies to show including houses to flats, shops to flats, commercial/ industrial units to flats and offices to flats under Prior Approval. Please see our Case Studies page for more information. 

What information do I need to provide the council for established use?

For flats:

• Tenancy agreements (for a period of 10+ years or 4 years prior to 25/04/2024)
• Council tax bills for each flat
• Utility bills addressed to each flat
• Affidavit*
• Statutory declaration*
• Receipt/Invoice from builders
• Photographs with dates
• Certificate of completion of works from Building Control
• Electoral roll for each flat
• Vehicle registration
• Maintenance bills

* Please note - a statutory declaration is not usually sufficient on its own and the Council are likely to expect other evidence as well, so that the balance of probability is in favour of the established use.

HMOs and Commercial Properties - 10 years rule

What about HMOs and commercial properties?

For commercial properties or houses of multiple occupation (HMOs) that have been in use over 10 years:

• Tenancy agreements
• Proof of rental income
• Bank statements showing rent payments
• Email communication with tenants
• Deposit protection certificates
• Affidavit or statutory declaration from tenants, neighbours or builders (signed by a solicitor)
• Letting agent confirmation letters
• Receipts or invoices from builders
• Photographs with dates
• Building Control completion certificate
• Electoral roll records for each tenant
• Utility bills addressed to tenants
• Vehicle registration documents showing the property address
• Vehicle maintenance or insurance documents showing the address
• TV licence records
• Landlord insurance policies referencing HMO use
• Fire alarm servicing certificates
• Emergency lighting certificates
• Waste collection arrangements
• Inventory check in / check out reports
• Historic property advertisements (Rightmove, Zoopla, SpareRoom, Gumtree etc.)
• HMO licence covering part or all of the 10 year period
• Old floor plans showing HMO layout
• Council tax records

The above list is only a summary of the most common evidence materials that may be accepted by the council, and is not exhaustive. For specific advice regarding your established use application, please contact a planning consultants at 4D Planning.

What the applicant needs to prove:

It is up to the person applying for a Lawful Development Certificate for an existing use to show the proper evidence. This could include:

• proof that any building was 'substantially complete' more than ten years before the date of the application 
• proof that any use (or breach of condition) has been carried on continuously for a period of 10 years (four years in the case of a dwelling prior to 25th April 2024)

If the LPA has evidence, or reasonable grounds to believe, that the applicant’s claim is not correct, it may refuse a certificate.

Lawful development for listed buildings

Is there an established use (4 years or 10 years) for listed buildings?

Lawful development certificates are not relevant to situations where breaches of listed building or conservation area controls may be alleged.

The Levelling-up and Regeneration Act 2023 (LURA) received Royal Assent on 26 October, 2023, with secondary legislation finalised on 2 April 2024, bringing enforcement provisions into force. See Planning Act 2008 (Commencement No. 8) and Levelling-up and Regeneration Act 2023 (Commencement No. 4 and Transitional Provisions) Regulations 2024. 

Section 115 revoking the four-year time limit for enforcement actions, extending it to 10 years for all breaches of planning control. This applies to operational development and change of use of any building to use as a single dwellinghouse.

The new provisions have come into force on 25th April 2024. The transitional provisions mean that this change will not apply in the following circumstances:  

• Where the operational development was substantially completed before 25th April 2024.
• Where the change of use to a dwelling occurred before 25th April 2024.

Provided that the above criteria can be met, then the four-year rule would remain.

Therefore if you have 4 years of evidence and you would like to apply for a lawful development certificate for your extension or conversion, now is the best time to apply as the transition period is still ongoing.

4D Planning can assist with the application and all the relevant drawings, maps, statement and paperwork. Contact Us today for a free consultation.