Buying a Block of Flats: MUFB Valuation, Stamp Duty and Title Splitting

Buying a whole block of flats on one freehold title can be one of the most efficient ways to grow a portfolio. But three things decide whether the numbers work: how the lender values the block, how much stamp duty you pay, and whether you can add value later by splitting the title. This guide goes deeper than our MUFB overview: https://www.dynesourcer.co.uk/blog/complex-btl/mufb-mortgage-multi-unit-freehold-block

Valuation: why the block is worth less than its flats

Surveyors usually report two figures for an MUFB:

• Block value: what the whole building would fetch as one lot. Fewer buyers can purchase a whole block, so this is normally discounted. • Aggregate value: the total if each flat were sold separately on its own lease.

The gap between the two is often 10% to 25%, depending on the location and condition. Most lenders lend against the block value, so your deposit is based on the lower figure. For larger blocks, some lenders use an investment value based on total rent and a market yield.

Stamp duty: the six-dwelling rule

Multiple dwellings relief was abolished from 1 June 2024, so most block purchases now pay standard residential rates on the whole price, plus the 5% surcharge for additional properties. There is one important exception.

If you buy six or more dwellings in a single transaction, you can choose to use non-residential rates instead: 0% up to £150,000, 2% from £150,001 to £250,000 and 5% above £250,000.

Illustrative comparison

A 4-flat block at £400,000: residential rates with 5% surcharge £30,000. Non-residential rates are not available (fewer than 6 dwellings).

A 6-flat block at £600,000: residential rates with 5% surcharge £50,000. Non-residential rates £19,500.

On a six-flat block, that election can save £30,500. Your conveyancer must confirm it applies and file the return correctly. Rates shown are for England and Northern Ireland.

Title splitting: adding value later

Some investors buy an MUFB on one title, then grant a long lease on each flat. That can:

• Raise the value towards the aggregate figure, because each flat becomes individually mortgageable and saleable. • Give more lender choice, since standard buy-to-let lenders can fund individual leasehold flats. • Let you sell flats individually if you want to release capital.

It also brings costs and risks:

• Lender consent is needed if the block is mortgaged. • Legal fees for drafting leases, plus land registry plans for each flat. • Building standards. Each flat needs to meet building regulations and fire safety rules. Conversions without building control sign-off can stop a split. • Leasehold rules keep changing, so take legal advice on lease terms before you split. • Tax. Selling flats later may trigger capital gains tax, or income tax if HMRC sees it as trading.

Some lenders will lend on an expected post-split value for refinancing, but usually only once the leases are registered.

Run the numbers before you offer

Select MUFB in the complex BTL calculator to test rental cover on the whole block. Our broker team can check unit limits and valuation basis before you pay for a survey.

Compare MUFB block purchases in the complex BTL calculator. HMO, MUFB, MPOT, short-term let, holiday let and other specialist property types all use this same tool.

https://www.dynesourcer.co.uk/mortgages/complex-buy-to-let-mortgage-calculator

For standard single-let buy-to-let mortgages:

https://www.dynesourcer.co.uk/mortgages/buy-to-let-mortgage-calculator

FAQs

Is there stamp duty relief for buying a block of flats

Multiple dwellings relief ended in June 2024. Buying six or more dwellings in one transaction lets you elect non-residential rates instead.

Will the lender lend on the aggregate value

Usually not. Most lend on the block value.

How long does a title split take

Typically several months, depending on lender consent, lease drafting and the Land Registry.

Can I split the title and refinance straight away

Some lenders allow it once the leases are registered; others want a period of ownership first.

Important information

Your property may be repossessed if you do not keep up repayments on your mortgage. Most buy-to-let mortgages are not regulated by the Financial Conduct Authority. Consumer buy-to-let mortgages, and mortgages where you or a close family member will live in the property, are regulated. Dynesourcer Ltd is an Introducing Appointed Representative of Dynamic Commercial Finance Ltd, which is authorised and regulated by the Financial Conduct Authority, FRN 946483. A broker fee may be payable on application; we will tell you the amount before you proceed. This article is general information, not personal advice or tax advice. Tax treatment depends on your individual circumstances and may change. Figures correct as at 29 October 2026.