Additional Property SDLT Surcharge: The Complete Guide for Conveyancers

Introduction

The additional property surcharge — formally the "higher rates for additional dwellings" — is one of the most complex areas of SDLT. At 5% on top of standard rates, it adds substantial cost to transactions, and the rules for when it applies are full of traps for the unwary.

This guide covers the surcharge from the conveyancer's perspective: when it applies, when it does not, how replacement of main residence works, the company purchase rules, and how to handle refund claims when circumstances change after completion.

Quick calculation: Our SDLT Calculator handles all additional property scenarios, including combined surcharges with non-resident status.

Current Rates with the Surcharge (2026/27)

The surcharge is added to each standard residential band:

Worked Example: £350,000 Buy-to-Let

Standard rates:

• £125,000 at 0% = £0
• £125,000 at 2% = £2,500
• £100,000 at 5% = £5,000
• Standard total: £7,500

With additional property surcharge:

• £125,000 at 5% = £6,250
• £125,000 at 7% = £8,750
• £100,000 at 10% = £10,000
• Total with surcharge: £25,000

The surcharge adds £17,500 to this transaction — more than double the base SDLT.

When Does the Surcharge Apply?

The surcharge applies when all of the following conditions are met:

1. The purchase is of a residential dwelling (property types 01 or 04 in HMRC classification)
2. The purchase price is £40,000 or more
3. At the end of the day of the transaction, the purchaser owns two or more residential properties (including the one just purchased)
4. The property being purchased is not replacing the purchaser's only or main residence

Key Points

• The test is based on ownership at the end of the effective date, not at the time of exchange
• Worldwide property ownership counts — not just UK properties
• A major interest (freehold or lease over 21 years at grant) in a dwelling is what triggers the test
• The surcharge applies to the entire purchase price, not just a portion above a threshold

When the Surcharge Does NOT Apply

1. Replacement of Main Residence

The most important exemption. The surcharge does not apply if:

• The purchaser is replacing their only or main residence
• The previous main residence is sold (disposed of) within 36 months of the purchase of the new one (or before the purchase)

If the old property is sold before or on the same day as the new purchase, no surcharge is payable at all. If it is sold within 36 months after, a refund can be claimed.

2. Purchase Price Under £40,000

Transactions below £40,000 are exempt from the surcharge, regardless of the purchaser's other property holdings. This catches some low-value leasehold transactions.

3. Properties That Are Not Dwellings

The surcharge only applies to dwellings — properties used or suitable for use as a residence. Commercial property, agricultural land, and mixed-use property are not subject to the surcharge (though they may attract the standard non-residential or mixed-use SDLT rates).

4. Certain Inherited Properties

A property inherited within the 36 months before the transaction does not count as an additional property if the purchaser holds a 50% or less share of it. This prevents joint inheritances from accidentally triggering the surcharge.

Joint Purchasers

The rules are tested separately for each purchaser. The surcharge applies if any purchaser meets the conditions.

Common Scenarios

Scenario 1: Couple buying together, one owns a buy-to-let The surcharge applies. One purchaser owns an additional dwelling at the end of the day.

Scenario 2: Couple buying together, one owns a property but is selling it on the same day The surcharge does not apply, provided the property being sold was that purchaser's only or main residence and the sale completes on or before the purchase.

Scenario 3: Parent helping child buy, parent is on the mortgage (and title) If the parent is named as a purchaser and owns their own home, the surcharge applies. This catches many families who add a parent to the title for mortgage purposes.

Practical Advice

Where possible, structure transactions to avoid unnecessary additional purchasers. If a parent does not need to be on the title (for example, if they are providing a gift deposit but the child can qualify for the mortgage alone), keeping them off the purchase avoids the surcharge.

Company Purchases

Companies buying residential property face specific rules:

Companies Purchasing for £500,000 or More

A flat rate of 17% applies to the entire purchase price. This single rate replaces both the standard banded rates and the additional property surcharge.

This applies to:

• UK and non-UK companies
• Partnerships where a partner is a company
• Collective investment schemes

Companies Purchasing Below £500,000

Standard banded rates plus the 5% surcharge apply (the same as for individual additional property purchases). The flat 17% rate only kicks in at £500,000.

Worked Example: Company at £600,000

• Flat 17% on £600,000 = £102,000

Compare to an individual paying the surcharge:

• £125,000 at 5% = £6,250
• £125,000 at 7% = £8,750
• £350,000 at 10% = £35,000
• Individual total: £50,000

The company rate is more than double. This is a deliberate deterrent against corporate ownership of residential property.

Non-Resident + Additional Property

Both surcharges can apply simultaneously. A non-UK resident purchasing an additional property pays:

Worked Example: Non-Resident Additional at £500,000

• £125,000 at 7% = £8,750
• £125,000 at 9% = £11,250
• £250,000 at 12% = £30,000
• Total: £50,000

On the same property, a UK-resident first-time buyer would pay £10,000. The difference — £40,000 — illustrates why it is critical to get the buyer classification right.

Refund Claims: The 36-Month Window

If the surcharge is paid because the purchaser had not yet sold their previous main residence, a refund can be claimed once the sale completes — provided it happens within 36 months of the purchase.

How to Claim

• The claim must be made within 12 months of the sale of the previous property (or 12 months after the filing date, whichever is later)
• Use HMRC's online amendment process or write to HMRC
• The refund covers the surcharge amount only (5%), not the base SDLT
• Interest is payable by HMRC on the refund from the date the surcharge was paid

Practical Tips

1. Diary the deadline — 36 months from purchase is the hard cut-off for the sale
2. Advise the client in writing — at completion, confirm the refund possibility and the deadline
3. Keep the SDLT5 — the UTRN is needed for the refund claim
4. Consider undertaking the refund claim yourself — it is a straightforward process and a useful touchpoint with the client

What If the Sale Falls Through?

If the client's old property sale falls through and they cannot sell within 36 months, the surcharge becomes final. There is no further recourse unless HMRC extends the deadline (which they have done in exceptional circumstances, such as during COVID-19).

Separation and Divorce

Special rules apply when the surcharge interacts with relationship breakdown:

• A decree absolute (or final order) means the former spouse's property ownership is no longer attributed to the purchaser
• Before the decree, the former matrimonial home may still count as an additional property
• Financial consent orders — the timing of property transfers under consent orders affects when the additional property test is applied

This is a specialist area and clients in this situation should be advised to take specific tax advice.

Key Takeaways for Conveyancers

1. 5% surcharge on all bands — not just above a threshold
2. Main residence replacement is the key exemption — 36-month window
3. Joint purchasers — test each individually, any trigger applies to all
4. Companies at £500k+ — flat 17%, no banding
5. Non-resident + additional — both surcharges stack
6. Refunds — claim within 12 months of selling the old property
7. Always ask — what other properties does the purchaser (and any joint purchaser) own?

Related Guides

• First-Time Buyer SDLT Relief — the relief your buyer might qualify for instead
• SDLT Rates 2026: Complete Guide — all current rates including surcharges
• SDLT Reliefs and Exemptions — replacement of main residence and other reliefs

Calculate additional property stamp duty instantly with our free SDLT Calculator — handles all surcharge combinations.

Is your firm ready for the May 2026 tax adviser registration deadline? Use our Compliance Checker to find out.