Selling property in the UK can trigger significant capital gains tax (CGT) liabilities if homeowners overlook key rules or miscalculate their obligations. From missed reliefs to reporting errors, these missteps often lead to unexpected bills, penalties, or even HMRC investigations. Below are the most common – and costly – CGT mistakes, along with actionable strategies to avoid them.
1. Assuming All Property Sales Are Tax-Free
The Mistake: Many homeowners wrongly believe selling their main residence is always exempt from CGT. While Private Residence Relief (PRR) covers most cases, exceptions apply. For example, if the property was rented out, used for business, or includes extensive land (over 0.5 hectares), partial CGT may still apply.
The Fix: Calculate PRR based on the proportion of time the property was your sole residence. Even one year of renting could reduce relief.
2. Overlooking Allowable Expenses
The Mistake: Homeowners often forget to deduct allowable costs when calculating gains, leading to inflated tax bills. This includes solicitors’ fees, stamp duty, and renovation expenses like extensions (but not basic repairs).
The Fix: Maintain detailed records of all buying, selling, and improvement costs. A £15,000 kitchen upgrade could reduce your taxable gain by the same amount.
3. Missing the 60-Day Reporting Deadline
The Mistake: Failing to report property sales and pay CGT within 60 days of completion – a rule introduced in 2020. Delays incur automatic penalties of £100, plus interest.
The Fix: Use HMRC’s Real-Time Capital Gains Tax Service to report promptly. Non-residents must report even if no tax is due.
4. Ignoring Annual Exemptions
The Mistake: For the 2023/24 tax year, individuals have a £6,000 CGT allowance. Many forget to offset this against gains or spread sales across tax years to maximise relief.
The Fix: If selling multiple assets (e.g., shares and property), apply the exemption to the highest-taxed gain first.
5. Misapplying Lettings Relief
The Mistake: Lettings Relief can reduce CGT if you rented part of your home, but stricter 2020 rules now cap it at £40,000 and only apply if you shared occupancy with tenants
The Fix: Confirm eligibility before claiming. A homeowner renting their entire property no longer qualifies.
6. Underpaying Due to Incorrect Tax Rates
The Mistake: Applying the wrong CGT rates. Residential property gains are taxed at 18% (basic rate) or 28% (higher rate), while other assets (e.g., shares) have lower rates.
The Fix: Calculate your taxable income first – exceeding the £50,270 higher-rate threshold by even £1 pushes gains into the 28% bracket.
7. Neglecting Spousal Transfers
The Mistake: Not leveraging a spouse’s tax-free allowance. Gifting a property share to a partner before selling can double reliefs and exemptions.
The Fix: Transfer ownership at least 12 months before sale to qualify for joint PRR and allowances.
8. Mishandling Inherited Properties
The Mistake: Assuming inherited homes are automatically CGT-free when sold. Tax applies only on gains made after inheritance, based on the probate value.
The Fix: Obtain a professional valuation at the time of inheritance. Selling quickly (in the same tax year) minimises gains.
9. Forgetting Overseas Liabilities
The Mistake: Non-residents selling UK property often misreport gains or miss the 60-day rule, risking penalties up to 200% of owed tax under HMRC’s offshore crackdown.
The Fix: Use the Residential Property Service for reporting and consult an offshore tax specialist for dual-residency scenarios.
10. Skipping Professional Advice
The Mistake: DIY tax calculations often lead to errors in complex cases, such as business-use properties or cross-border transactions.
The Fix: A capital gains tax accountant can identify overlooked reliefs, ensure accurate reporting, and represent you during HMRC enquiries.
Final Tip:
HMRC’s Connect system now cross-references land registry data, mortgage records, and even rental websites to flag discrepancies. Proactive compliance is non-negotiable. By partnering with a capital gains tax accountant from Tax Accountant UK, homeowners can avoid these pitfalls, leverage reliefs strategically, and protect their profits.
Visit Tax Accountant UK for tailored capital gains tax advice and dispute resolution.
