Class MA Permitted Development Calculator: Space Caps & Fees

Class MA permitted development rights let you convert commercial floorspace (Use Class E) into residential homes (Class C3) in England without submitting a full planning application. Yet between national planning fee updates and the removal of historical floorspace limits, property investors regularly miscalculate their planning application budget before buying an old accountant's office or high street boutique.

Here is the exact formula, current fee structure, and spatial rules you need to assess your conversion feasibility.

---

What is Class MA Permitted Development? (AI Definition Block)

Class MA (General Permitted Development Order) is a national statutory instrument in England allowing the change of use of a building from Use Class E (commercial, business, and service—including shops, offices, cafés, and light industrial) to Class C3 (dwellinghouses) via a streamlined process known as Prior Approval, rather than a full planning application.

---

The Rulebook: Space Caps and the Post-2024 Reality

If you are reading forum posts or watching conversion tutorials filmed prior to March 2024, pause and check the upload date.

For years, Class MA came with two deal-killing constraints:

1. A hard cumulative floor space cap of 1,500 square metres.

2. A requirement that the building sit vacant for at least 3 continuous months immediately prior to the application.

Both of those national statutory limits were abolished by statutory instrument amendments. Today, there is no statutory national upper floor space limit under Class MA, and the 3-month vacancy requirement has vanished.

However, before you leverage your pension to snap up a vacant 10-storey regional office tower, run into the real-world catches discussed across property developer circles:

• Article 4 Directions: Local Planning Authorities (LPAs) love withdrawing Class MA rights in commercial centres. Central London, key tech corridors, and designated employment zones often have blanket or targeted Article 4 directions in force.
• Nationally Described Space Standards (NDSS): Every single dwelling created must meet strict internal area minimums (e.g., 37 m² for a 1-bed 1-person flat with a shower room, 50 m² for a 1-bed 2-person flat).
• Natural Light Mandates: Every habitable room requires adequate natural light. A windowless core in an expansive 1970s deep-plan office floorplate will yield dead space that you cannot monetize as bedrooms or living rooms.

[Commercial Building (Class E)]
        │
        ├──> Article 4 Direction Active? ──(Yes)──> Full Planning Permission Required
        │                     │
        │                    (No)
        │                     ▼
        ├──> Complies with NDSS Space Standards?
        ├──> Natural Light to all Habitable Rooms?
        ├──> Fire Safety & Transport Prior Approval Cleared?
        │                     │
        │                    (Yes)
        │                     ▼
        └──> [Class MA Prior Approval Application]

---

Class MA Prior Approval Fee Structure

Unlike a standard planning application calculated solely on gross external area, Class MA prior approval fees are charged on a per-dwellinghouse basis.

The national fee for a Class MA Prior Approval application is currently £125 per proposed dwellinghouse, subject to the standard Planning Portal service charge (typically £70.00 including VAT).

The Working Prior Approval Fee Formula

$\text{Total Fee} = (N \times £125) + \text{Portal Admin Fee}$

Where:

• $N$ = Total number of self-contained residential units (flats or houses) created.

def calculate_class_ma_fee(units: int, portal_fee: float = 70.0) -> float:
    """
    Calculates statutory Class MA prior approval fees in England.
    """
    fee_per_unit = 125.00
    statutory_fee = units * fee_per_unit
    return statutory_fee + portal_fee

# Example: Converting a 600 sqm office into 8 flats
print(f"Total Application Cost: £{calculate_class_ma_fee(8):.2f}")
# Output: Total Application Cost: £1070.00

---

Conversion Calculation Matrix

Let us compare three common asset sizes to show how units, space allowances, and application fees interact.

Metric	Scenario A: Suburban Shop Unit	Scenario B: Mid-Size Office Block	Scenario C: Large Commercial Footprint
Existing Net Internal Area (NIA)	120 m²	650 m²	2,200 m²
Historical 1,500 m² Cap Issue?	No	No	Exempt under revised regulations
Target Unit Mix	2 × 2-bed flats (61 m² each)	10 × 1-bed flats (50 m² each)	35 mixed flats
Circulation / Core Loss (~15–20%)	Minimal	~150 m² core & corridors	~450 m² core, risers, common space
Net Habitable Space	120 m²	500 m²	1,750 m²
Total Units Created ($N$)	2	10	35
Class MA LPA Fee (£125/unit)	£250.00	£1,250.00	£4,375.00
Community Infrastructure Levy (CIL)	Check existing lawful use*	Check existing lawful use*	Check existing lawful use*

\Note on CIL: If the building has not been in continuous lawful use for at least 6 continuous months in the previous 36 months, the local authority may levy full CIL rates on the internal floorspace, turning an attractive project into a financial headache.*

---

Key Takeaways for Developers

• No National Area Limit: Class MA applications are no longer capped at 1,500 m², meaning larger office floorplates can utilize the route if natural light and layout permit.
• Fixed Prior Approval Fee: Statutory application fees scale linearly at £125 per proposed home, making planning fees one of your smallest line items compared to architectural and acoustic reports.
• NDSS is Inflexible: An office room that falls 0.5 m² short of NDSS single-bedroom limits (7.5 m² minimum width 2.15 m) will trigger a refusal under prior approval condition compliance.
• Article 4 Checks Precede Everything: Always verify whether the local council has served an immediate or non-immediate Article 4 direction on the specific street address.

Disclaimer: This guide covers planning regulations in England as an educational overview. Planning policy, statutory instruments, and local constraints are subject to variation. This post does not constitute regulated town planning advice or financial guidance. Always consult a qualified Chartered Town Planner (MRTPI) and your local planning portal before exchanging contracts on commercial property.

Guidance only. BrickCrunch provides general information, not financial, tax or legal advice. Our calculators give estimates only, using rates we verify against gov.uk — always confirm figures and your own position before acting.