When Does a Change of Use Actually Begin? Lessons from Class MA Case Law

In the world of permitted development rights (PDR), timing is everything. Especially under Class MA of the General Permitted Development Order (GPDO), which allows the conversion of Class E commercial premises to residential use, one crucial question repeatedly arises: when is a change of use considered lawfully “begun”?

This matters because under Class MA, developers have just three years from the date of prior approval to complete the change of use. But what counts as “completion”? And how do you prove you’ve started on time if the flats aren’t yet finished—or even occupied?

Implementation Isn’t Always About Occupation

Contrary to common belief, actual occupation isn’t needed to show that a change of use to residential has occurred. Courts and planning inspectors have consistently held that a material change of use can take place before anyone moves in, so long as the building has been sufficiently prepared and dedicated to the new use.

This principle stems from landmark cases like Impey v SSE and was recently affirmed in both High Court judgments and Planning Inspectorate decisions involving Class MA and its predecessors. What matters is a fact-and-degree judgment: has the building, in practical terms, transitioned from one use to another?

The Bromley Case: A Blueprint for Implementation

One of the clearest illustrations comes from a 2020 appeal concerning a developer in Bromley. They’d obtained prior approval to convert an office into eight flats. By the deadline, only one flat was finished and occupied; the others were partially built—some even lacking bathrooms.

Was that enough to “complete” the change of use under the GPDO?

The inspector said yes. Why? Because the office use had ceased, and the building had irreversibly become a residential scheme. The layout, services, and internal works clearly showed intent and progress. Even without full completion, the change of use had begun in a meaningful, lawful way.

Use vs. Works: What’s Really Required?

So what’s the takeaway for developers?

• Commencement doesn’t require full occupation, but it does require clear, tangible evidence that the change of use is underway.

• Substantial fit-out works, such as forming rooms, installing services, and preparing the building for residential life, can be enough.

• Cessation of the old use (like ending office operations) is a strong signal that the new use has taken hold.

• Token works or unrelated refurbishments won’t cut it—your actions must clearly further the new residential use.

  
  

And above all: document everything. From photos to floor plans, marketing materials to utility connections, evidence is your best defence if a lawful implementation is ever challenged.

Planning for Success

Understanding when a change of use is “implemented” can mean the difference between securing your PDR and losing it entirely. With case law increasingly favouring a pragmatic, real-world view, the message is clear: if the old use is gone, and the new one is physically and functionally underway, then you’re likely on solid ground.

But don’t leave it to chance. Get advice early, act promptly—and keep a paper trail.

When does residential use under Class MA begin?