Calculating Capital Gains Tax (CGT) can seem complicated, but understanding the rules is essential for anyone selling assets, property, or investments in the UK. Miscalculating CGT can lead to unexpected liabilities and penalties from HMRC. Whether you are an individual investor, property owner, business owner, or involved in cryptocurrency trading, understanding how to calculate your capital gains tax correctly is crucial for effective financial planning.
At ABM Chartered Accountants, a trusted accounting firm in Canary Wharf, we provide expert guidance on CGT, helping our clients maximise allowances, claim reliefs, and ensure full compliance with HMRC regulations. This detailed guide will explain step-by-step how CGT is calculated, the types of assets affected, exemptions, reliefs, reporting requirements, and practical tax planning strategies.
What is Capital Gains Tax?
Capital Gains Tax is a tax applied to the profit or “gain” you make when you sell or dispose of an asset that has increased in value. It is important to note that CGT is charged on the gain, not the total sale price.
Common Situations Where CGT Applies
- Sale of residential property that is not your main home
- Sale of shares, stocks, or other investments
- Disposal of cryptocurrencies
- Sale or transfer of business assets
- Sale of valuable personal possessions exceeding £6,000, such as art, antiques, or jewellery
- Gifts of assets to individuals other than a spouse or civil partner
It is crucial to understand that CGT applies to individuals, sole traders, and partnerships. Companies are not liable for CGT; instead, they pay Corporation Tax on chargeable gains.
Step-by-Step Guide to Calculating Capital Gains Tax
Calculating CGT requires a structured approach. Below is a detailed five-step process:
Step 1: Determine the Sale or Disposal Value
The first step is to identify the value received when you dispose of the asset. This is usually the selling price. If the asset is gifted, CGT is based on the market value at the time of transfer.
Step 2: Deduct the Purchase or Acquisition Costs
The gain is calculated by subtracting the original cost of acquiring the asset from the sale value. This includes:
- Purchase price
- Stamp duty or registration fees
- Professional fees, such as legal or estate agent costs
- Capital improvements (excluding maintenance or repairs)
Step 3: Deduct Allowable Expenses
You can also deduct expenses directly associated with the sale or disposal of the asset. Common allowable expenses include:
- Selling or advertising costs
- Transaction fees or broker commissions
- Legal and professional fees incurred during the sale process
Step 4: Apply Tax-Free Allowances and Reliefs
Each individual has a tax-free Annual Exempt Amount (AEA). For the 2025/26 tax year, the AEA is:
- £3,000 for individuals
- £6,000 for married couples or civil partners if both allowances are combined
Reliefs such as Private Residence Relief or Business Asset Disposal Relief can further reduce the taxable gain.
Step 5: Apply the Relevant Capital Gains Tax Rate
The CGT rate depends on:
- Type of asset (residential property vs. other assets)
- Your income tax band (basic, higher, or additional rate taxpayer)
Capital Gains Tax Rates for 2025
Residential Property
| Income Tax Band | CGT Rate |
| Basic Rate | 18% |
| Higher & Additional Rate | 24% |
Other Assets (Shares, Crypto, Commercial Property, Antiques)
| Income Tax Band | CGT Rate |
| Basic Rate | 10% |
| Higher & Additional Rate | 20% |
Residential property gains are taxed at a higher rate to discourage speculative investment and ensure fairness in the housing market.
Detailed Examples of CGT Calculation
Example 1: Residential Property
Suppose you bought a rental property for £200,000 and sold it for £300,000. You also spent £10,000 on improvements.
Calculation:
- Sale proceeds: £300,000
- Purchase cost: £200,000
- Improvement costs: £10,000
- Gain = £300,000 – £200,000 – £10,000 = £90,000
- Deduct Annual Exempt Amount: £90,000 – £3,000 = £87,000 taxable gain
- If you are a higher-rate taxpayer, tax = 24%
- CGT owed = £87,000 x 24% = £20,880
Example 2: Shares
You purchased shares for £10,000 and sold them for £25,000, incurring £500 in broker fees.
Calculation:
- Gain = £25,000 – £10,000 – £500 = £14,500
- Deduct Annual Exempt Amount: £14,500 – £3,000 = £11,500 taxable
- If you are a basic-rate taxpayer, CGT = 10%
- CGT owed = £11,500 x 10% = £1,150
Example 3: Cryptocurrency
You bought Bitcoin for £5,000 and sold it for £12,000, paying £200 in transaction fees.
Calculation:
- Gain = £12,000 – £5,000 – £200 = £6,800
- Deduct Annual Exempt Amount: £6,800 – £3,000 = £3,800 taxable
- CGT rate for a higher-rate taxpayer = 20%
- CGT owed = £3,800 x 20% = £760
Assets Exempt from Capital Gains Tax
Certain assets are fully or partly exempt from CGT:
- Main residence (Private Residence Relief applies)
- Cars and personal vehicles
- ISAs (Individual Savings Accounts)
- National Savings & Investments (NS&I) Certificates
- UK government bonds (“gilts”)
- Personal possessions sold for less than £6,000
Understanding exemptions is essential to reduce your tax liability legally.
Reporting and Paying Capital Gains Tax
Residential Property
For UK residential property, you must report and pay CGT within 60 days of completion of the sale. This is a strict HMRC requirement, and late payments incur interest and penalties.
Other Assets
For other assets, gains are usually reported through the Self Assessment tax return. The payment deadline is 31 January following the end of the tax year in which the gain occurred.
Failing to report gains correctly can result in penalties, interest, and increased scrutiny from HMRC.
Strategies to Minimise Capital Gains Tax
While CGT cannot be avoided entirely, there are legal ways to reduce your liability:
1. Utilise Your Annual Exempt Amount
Ensure that you use your tax-free allowance each year. Failing to use it can result in avoidable tax payments.
2. Transfer Assets to a Spouse or Civil Partner
Transfers between spouses are tax-free and allow you to combine allowances, effectively doubling the tax-free threshold.
3. Use Tax-Wrapped Investment Accounts
Investments held in ISAs, pensions (SIPPs), or life insurance bonds are exempt from CGT, allowing tax-free growth.
4. Offset Gains with Capital Losses
Capital losses can be offset against current or future gains, reducing your CGT liability.
5. Claim Business Asset Disposal Relief (BADR)
This relief, formerly known as Entrepreneurs’ Relief, reduces CGT to 10% on qualifying gains for business owners who dispose of all or part of their business.
6. Consider the Timing of Disposal
Selling assets after the start of a new tax year can reset your annual exemption and may reduce your taxable gain.
7. Claim Private Residence Relief
If a property was your main home for part of the ownership period, Private Residence Relief may apply, reducing the taxable gain proportionally.
Capital Gains Tax on Cryptocurrency
HMRC treats cryptocurrencies as assets for CGT purposes. You must pay tax when you:
- Sell crypto for cash
- Trade one cryptocurrency for another
- Use crypto to pay for goods or services
Mining and staking rewards may be considered income, subject to income tax, rather than capital gains.
CGT for Non-UK Residents
Non-residents are liable to CGT only on UK property and land. Non-residents must comply with the 60-day reporting deadline. Double taxation treaties may prevent paying CGT twice, depending on the country of residence.
Capital Gains Tax for Companies
Companies do not pay CGT. Instead, chargeable gains are included in taxable profits for Corporation Tax purposes. Adjustments may include indexation allowances (for gains before 2018) and treatment of losses differently than for individuals.
Common Capital Gains Tax Mistakes to Avoid
- Not deducting all allowable costs – many sellers forget improvements and fees.
- Missing reporting deadlines – HMRC applies penalties for late submission.
- Failing to use tax-free allowances – every year counts.
- Assuming cryptocurrency is tax-free – HMRC clearly treats crypto as taxable.
- Confusing CGT with income tax – different rates and rules apply.
- Ignoring losses – unclaimed losses could reduce future CGT liability.
- Selling all assets in a single tax year – consider spreading disposals strategically.
Why Professional Help is Recommended
Capital gains tax becomes particularly complex when multiple assets, foreign investments, or business disposals are involved. A specialist accountant can:
- Ensure accurate calculation of gains and allowances
- Identify applicable reliefs and exemptions
- Provide effective tax planning to minimise CGT
- Assist with HMRC reporting and compliance
- Prevent costly mistakes and penalties
At ABM Chartered Accountants, we help individuals, landlords, and businesses navigate CGT efficiently. Our expertise ensures compliance while maximising legitimate savings.
Why Choose ABM Chartered Accountants?
ABM Chartered Accountants is a full-service accounting firm based in Canary Wharf, offering expert advice on:
- Residential and commercial property gains
- Share and investment disposals
- Cryptocurrency and digital assets
- Business asset sales and restructuring
- CGT planning and reporting
- HMRC compliance and dispute resolution
Our team stays updated with the latest tax legislation to provide precise advice tailored to your financial situation. We help clients strategically plan asset disposals, reducing their capital gains tax liability legally.
Final Thoughts on Capital Gains Tax
Capital Gains Tax is a complex but manageable aspect of personal and business finance. Accurate calculation, proper reporting, and effective tax planning are essential to avoid penalties and reduce liabilities. With professional support, you can ensure compliance, use available reliefs efficiently, and optimise your financial outcomes.
If you are looking to calculate your capital gains tax accurately or need expert advice on minimising your liability, ABM Chartered Accountants is here to help. Our team of experts specialises in property, investments, business disposals, and cryptocurrency tax planning, ensuring you keep more of your gains while remaining fully compliant with HMRC regulations.
Frequently Asked Questions (FAQs)
Do I pay CGT if I gift property to my child?
Yes, unless the transfer is to a spouse or civil partner. Market value at the time of transfer is used for calculation.
Do I pay CGT on inherited property?
No, inheritance itself is not subject to CGT. You pay tax only when you sell the inherited asset.
Can CGT be avoided entirely?
No, but legal strategies such as using exemptions, allowances, and reliefs can minimise the amount owed.
Is CGT the same as inheritance tax?
No. CGT applies on gains from the sale or disposal of assets, whereas inheritance tax is levied on estates after death.
