Capital Gains Tax Calculator UK
Selling an asset that has increased in value? Use our Capital Gains Tax Calculator UK to estimate the Capital Gains Tax (CGT) you may have to pay. Enter details about your purchase price, selling price, and allowable costs to estimate your capital gain, taxable gain, and potential Capital Gains Tax.
CAIL can help you calculate your potential tax liability, understand allowable costs and reliefs, and meet your reporting obligations. Our Capital Gains Tax Calculator is a useful tool for estimating your potential CGT.
How to Use the Capital Gains Tax Calculator UK?
Here are the straightforward steps to use this tool:
Enter Your Total Gain
Add the sale price (or market value) minus what you originally paid, minus allowable costs like legal fees or improvements.
Enter Your Taxable Income
Include your taxable income for the year, since this determines what rate applies to your gain.
Select the Asset Type
Select whether you sold property, shares, or personal possessions.
Get Your Results
The calculator estimates your taxable gain after allowable costs, losses and the annual exempt amount, then applies the relevant CGT rate to estimate the tax you may owe.
How Does Capital Gains Tax Work?
Capital Gains Tax may apply when you dispose of an asset that has increased in value.
A basic calculation is:
Selling price − purchase price − allowable costs = Capital Gain
You may then deduct eligible losses, reliefs and the Annual Exempt Amount before calculating the tax due.
For individuals, the Annual Exempt Amount is £3,000 for the 2026/27 tax year.
Disclaimer: The rates mentioned above are based on the 2026/27 tax year. Tax rates and thresholds may change, so check the latest guidance before relying on these figures.
Why Use Our Capital Gains Tax Calculator UK?
Our Capital Gains Tax Calculator UK is a simple tool that helps you estimate your potential Capital Gains Tax before you make a tax return.
- Up to date with current tax year rates and allowances
- Works for shares, crypto, property and other assets
- Automatically applies your £3,000 tax-free allowance
- Free, instant, no sign-up needed
- Built by qualified London accountants
Selling a Property or Business Asset? Talk to Cheap Accountants in London
Capital Gains Tax has strict deadlines and valuable reliefs that are easy to miss without the right advice. At CAIL, our London team offers:
- CGT calculations and Self Assessment reporting
- 60-day property disposal reporting and payment
- Business Asset Disposal Relief eligibility checks
- Tax-efficient planning before you sell
- Affordable fixed-fee packages
Frequently Asked Questions
Do I pay CGT on my main home?
Usually not. Your main residence is generally exempt under Private Residence Relief, as long as you’ve lived in it throughout your ownership.
What costs can I deduct from my gain?
You can deduct the amount you originally paid for the asset, plus allowable costs such as legal fees, stamp duty on purchase, and money spent on improving the asset (not routine maintenance).
Do I need to report a gain if it's below my Annual Exempt Amount?
If your total gains are below the annual exempt amount and you’re not required to file a Self Assessment return for another reason, you generally don’t need to report it. Selling residential property has separate reporting rules regardless of the gain size.
What if I made a loss?
Capital losses can be offset against gains in the same year, or carried forward to reduce future gains, so it’s worth reporting losses even if you don’t currently owe any CGT.
Is this calculator accurate enough to file my return?
It gives a solid estimate, but reliefs like Private Residence Relief, BADR, or losses from previous years can significantly change your actual liability. So, it is best to confirm with an accountant before filing or paying.
Do I need to report capital gains to HMRC?
Yes, taxable gains must be reported through a self-assessment tax return or HMRC reporting system.
Do I pay Capital Gains Tax when I sell shares?
You may have to pay CGT when you sell shares for a profit, depending on your overall gains, losses, allowances and circumstances.
Looking for Cheap Accountants in London?
Get professional accounting support without paying for unnecessary services. Whether you need company accounts, a tax return, bookkeeping or another accounting service, we’ll help you find a solution that suits your business.