Combining Two Flats into One: What VAT Rate Applies?

Qualifying works to reduce the number of dwellings — for example, converting two flats into a single house — can attract the 5% reduced rate of VAT under HMRC Notice 708 Section 8. The key condition is that the number of separate dwellings in the building must decrease as a result of the works. This is a change-of-number-of-dwellings supply, not a general renovation. The 5% applies to the contractor's services on the qualifying works — not to materials you buy directly, and not to any works that do not form part of the dwelling-number reduction.

5% not 20%

Why this matters

On a £150,000 project to combine two flats, the difference between 5% and 20% VAT on the contractor's services is £22,500. Most contractors will default to 20% unless you specifically raise the dwelling-number change qualification and provide the necessary evidence before contracting.

The key distinctions

5% applies — qualifying change in number of dwellings

Works that convert two or more dwellings into fewer dwellings (e.g., two flats into one house) qualify for the 5% reduced rate under Notice 708 Section 8.2. The qualifying condition is a net reduction in the number of dwellings.

5% applies — renovation of long-empty dwellings

If the combined property has also been empty for 2+ years, the empty-property reduced rate (Section 8.3) may also apply. The two qualifying conditions can overlap.

20% applies — works unrelated to dwelling reduction

Any works on the property that are not directly associated with the change in number of dwellings remain at standard rate. For example, an extension that increases the floor area but is not connected to the flat-combination is a standard-rated supply.

Evidence required — planning permission or building control

The contractor will need to confirm the dwelling-number change is taking place. A planning permission or building control application showing the change from multiple to single dwelling is the standard evidence.

Practical checklist

Confirm the number of dwellings is being reduced as part of the works
Obtain planning permission or building control approval evidencing the dwelling-number change
Raise the qualifying condition with your contractor before signing the contract
Ask the contractor to apply 5% to qualifying works and 20% to any unrelated works
Keep the planning or building control documentation throughout the project
Check whether the property has also been empty for 2+ years — both reliefs may be available

HMRC notice references

HMRC Notice 708 Section 8.2—Change in number of dwellings — reduced rate conditions

HMRC Notice 708 Section 8—Qualifying reduced-rate renovation supplies

VATBuild is not affiliated with HMRC. References to HMRC publications are for informational purposes. Always consult a qualified tax adviser before making decisions about VAT on your project.

How VATBuild helps

What VATBuild checks for this situation

VATBuild identifies contractor invoices for projects involving a qualifying change in number of dwellings and confirms whether the 5% reduced rate has been applied. It flags any invoice line where 20% has been charged on qualifying works and identifies which contractors need to issue corrected invoices.

Empty property 5% VAT Builder charged 20% on renovation Renovation VAT rates explained