Common Mistakes That Lead to Overpaid Stamp Duty

Buying property in the UK is already a complex process, and overpaying Stamp Duty Land Tax (SDLT) makes it worse. Every year, thousands of buyers pay too much due to simple yet costly errors, often because of outdated advice or oversight by their solicitor.

Here are the most common mistakes in 2025 that lead to overpaid SDLT - and how SCA Tax can help you get a refund.

1. Using an Inaccurate SDLT Calculator

Free SDLT calculators can be misleading. Most of them:

• Don't account for non-residential or mixed-use elements
• Ignore edge-case reliefs or exemptions
• Aren’t updated for recent HMRC policy changes

Relying solely on these tools without professional input can result in you paying thousands more than required.

2. Misclassifying a Mixed-Use Property

Mixed-use properties - those with both residential and commercial elements - are eligible for non-residential SDLT rates. These include:

• Properties with shops, stables, or land used for commercial activity
• Homes with agricultural land or grazing paddocks
• Flat + shop combinations

Many buyers overpay because the solicitor assumes the entire property is residential without reviewing the land or outbuildings.

3. Paying the 5% Surcharge When You Shouldn’t

The SDLT surcharge for second homes was increased to 5% in June 2024. It applies to most additional residential properties, including buy-to-let investments and second homes.

However, many people still pay it in error, such as when:

• Replacing their main residence
• Buying jointly with someone who owns property but qualifies for exemption

If any of the following applies, you may be eligible for a refund:

• You sold your main residence within 36 months of the new purchase
• Your previous home was already sold before completion
• You qualified under one of HMRC’s narrowly defined exemptions

Considering the 5% rate now applies to the full purchase price, overpayments can be significant. On a £600,000 property, that’s an extra £30,000 in SDLT if applied incorrectly.

4. Assuming Your Solicitor Got It Right

Solicitors are essential in the legal transfer of property but are not tax specialists. Their job is to submit the SDLT return on time - not analyse whether you qualify for reliefs or exemptions. Many buyers assume their SDLT bill is correct when, in reality, a second opinion could reveal serious overpayments.

Avoiding These Costly Mistakes

To reduce the risk of overpaying SDLT:

• Double-check your SDLT return with a tax advisor
• Ask whether your property qualifies for non-residential rates
• Review whether any surcharges were applied incorrectly
• Get a second opinion - even after completion, you may still be in time to claim

Overpaid Stamp Duty? SCA Tax Can Help

SCA Tax specialises in identifying SDLT overpayments and preparing refund claims for HMRC. Our team has helped recover millions of pounds for clients across the UK.

• Free eligibility check
•  No-win, no-fee options
•  Expert handling of HMRC disputes

Think you might have overpaid stamp duty? Let’s find out.

Start your free assessment here.