How to Use Our Capital Gains Tax Calculator
Use our CGT Calculator to estimate how much tax you might owe when selling or gifting an asset. Simply enter your sale date, asset type, purchase and sale prices, and annual income.
The calculator will instantly work out your Capital Gains Tax liability, showing you exactly how much tax you may need to pay based on the current tax year’s rates and allowances.
Our calculations are based on official HMRC guidelines, providing an accurate estimate of your potential tax bill. However, you should always confirm your exact position with a qualified accountant or tax adviser, as personal circumstances can affect your final tax outcome.
How is Capital Gains Tax calculated in the UK?
CGT is a tax on the profit you make when you sell something (an asset) that has increased in value. Understanding how capital gains tax is calculated helps you estimate how much you will owe once a gain or loss becomes chargeable.
To calculate your tax bill, take your sale price, subtract your original purchase price, deduct any allowable costs (such as legal fees or estate agent fees), and then subtract your annual capital gains tax allowance. The resulting figure represents your taxable gains, which determine your tax liability. For the 2024/25 and the 2025/26 tax year, the gains tax allowance stands at £3,000 for individual taxpayers, meaning you don’t pay tax on gains below this threshold.
The rate of capital gains tax you pay depends on the type of asset you’ve sold and your income tax bracket. Most assets, including shares and investments like stocks, are taxed at 18% for basic rate taxpayers and 24% for higher rate taxpayers from 30 October 2024 onwards. Residential property (excluding your primary home) is subject to the same rates. If you sell property or other investments jointly with a spouse or civil partner, you each get your own allowance, potentially doubling your tax-free amount.
Special tax rules apply in certain situations. Business Asset Disposal Relief (formerly Entrepreneurs’ Relief) offers a reduced 10% rate on qualifying business disposals in 2024, rising to 14% in 2025. Carried interest from investment fund management has its own specific rates. To calculate your CGT accurately, you need to report and pay capital gains tax through your Self Assessment tax return, typically due by 31 January following the tax year after you profit from the sale.
See also: How to Register for Self Assessment Tax Return on GOV.UK
What is the capital gains tax allowance for 2024/25 and 2025/26?
The CGT allowance, also known as the Annual Exempt Amount, represents the profit you can make from selling assets before you need to pay any capital gains tax. For the tax year 2024/25 and 2025/26, this allowance is £3,000 for individuals, trustees of disabled persons’ trusts, and personal representatives. Other trustees receive a lower allowance of £1,500. These figures mark a significant reduction from £6,000 in 2023/24 and £12,300 in 2022/23.
If you make a capital gain of £5,000, you’ll subtract the £3,000 allowance, leaving £2,000 as your taxable gain. However, if you don’t use your allowance in a given year, you cannot carry it forward. Each taxpayer gets their own allowance, so couples can potentially shield £6,000 of gains tax-free by transferring assets between spouses before selling. Transfers to a spouse or civil partner are tax-free, making this a popular tax-planning strategy.
Certain investments offer additional tax-free benefits beyond the standard allowance. Shares held within an Individual Savings Account (ISA) grow completely tax-free, and you don’t pay capital gains tax when you sell them, regardless of the profit size. Similarly, investments held in these accounts, such as pensions, are protected from CGT. Your main home typically qualifies for Private Residence Relief, meaning you don’t pay gains tax when you sell your primary residence, though buy-to-let properties and second homes remain fully taxable.
Further reading: CGT Allowance 2024/25: How Much Is Capital Gains Tax and What’s Changing?
What are the current Capital Gains Tax Rates?
Capital gains tax rates in the UK changed significantly on 30 October 2024, affecting most asset types. Understanding these tax rates helps you estimate how much you may have to pay when you sell property, shares, or other investments. The rates you’ll pay depend primarily on which income tax band you fall into and what type of asset you’ve sold.
From 30 October 2024, most assets, including shares, cryptocurrency, and business assets, are taxed at 18% for gains that fall within your basic rate income band, and 24% for gains above this threshold. Residential property (excluding your primary home) follows the same 18%/24% structure. Before this date, non-property assets were taxed at the lower rates of 10% and 20%. The change means basic rate taxpayers now face significantly higher tax bills on investment gains.
Your total income affects which rate applies to your capital gain. If your salary and other income already push you into the higher rate bracket (above £50,270), all your capital gains will be taxed at the higher 24% rate. If you’re a basic-rate taxpayer, part of your gain may be taxed at 18% until your combined income and gains exceed £50,270, with the remainder taxed at 24%. This split calculation can significantly impact the tax you pay on larger gains.
Special rates apply in specific circumstances. Business Asset Disposal Relief offers a preferential 10% rate on qualifying business sales in 2024/25, though this relief is subject to a £1 million lifetime limit and increases to 14% from April 2025. Trustees pay a flat 24% on most gains and 28% on residential property gains. Professional tax advice can help you understand which rates apply to your situation and whether any tax relief might reduce your liability.
When do I need to pay Capital Gains Tax?
The deadline to pay gains tax depends mainly on what you’ve sold and how much you’ve gained. For most assets, you need to report and pay any CGT through your Self Assessment tax return. These returns cover the tax year running from 6 April to 5 April, and you must file by 31 January following the end of that tax year. For example, if you sold any stocks and shares in November 2024, you’d need to declare this on your 2024/25 tax return, due by 31 January 2026.
UK property sales are subject to stricter reporting requirements. If you sell property and owe capital gains tax on it, you must report and pay capital gains tax within 60 days of completion, regardless of when the tax year ends. You do this through the UK property reporting service on gov.uk, separate from your annual tax return. Missing this deadline results in penalties and interest charges. Even if you don’t ultimately owe tax due to reliefs or allowances, you still need to report if your total proceeds exceed four times the annual allowance (£12,000 for 2024/25).
Keep in mind that you may be subject to reporting requirements even when no tax is due. HMRC requires you to need to declare capital gains in your tax return if your total disposal proceeds exceed £50,000 in a tax year, or if your taxable gains (after deducting costs and losses but before the allowance) exceed the annual exempt amount. Some taxpayers who don’t usually complete a tax return may need to register for Self Assessment specifically to report capital gains.
Payment arrangements vary depending on your tax bill. Most people pay their capital gains tax liability in one lump sum by the deadline. However, if you’re due to pay a substantial amount and face financial difficulty, you can sometimes arrange a payment plan with HMRC. Interest accrues on any unpaid tax from the due date, and late payment penalties apply after 30 days, increasing at 6 and 12 months. Setting aside funds when you sell, rather than waiting until the deadline, helps avoid cash flow problems.
Also related: UK Tax Year Dates and Tax Returns Deadlines
Do I need to report and pay capital gains tax on shares?
Whether you need to pay gains tax on shares depends on several factors, including where you hold them, how much profit you make from selling them, and your total gains for the tax year. Shares bought and sold outside of a shares ISA or pension are subject to CGT on any gains, once you’ve used your £3,000 annual allowance. The profit from selling shares counts as a capital gain, not income, so different tax rules apply than for dividend income or salary.
When you sell something like shares, you calculate your gain by taking the sale proceeds, subtracting what you originally paid (including any purchase fees), and deducting allowable costs such as stockbroker fees or stamp duty. If you’ve bought shares in the same company at different times and prices, special matching rules determine which shares you’ve sold for tax purposes. The tax you pay when you sell depends on your income level and the size of your gain, with rates of 18% and 24% from 30 October 2024.
You don’t pay tax on shares held within ISAs or SIPPs (Self-Invested Personal Pensions). Money you make from selling shares inside these accounts remains completely tax-free, regardless of the gain. Annual ISA contribution limits restrict how much you can shelter (£20,000 for 2024/25), but any growth within the ISA stays protected. Many investors prioritise filling their ISA allowance each year to minimise future tax on investment gains they make when markets rise.
Even if you owe no tax, you might still need to declare your share sales. You need to report share disposals in your Self Assessment tax return if your total proceeds (not just gains) exceed £50,000 in a tax year, or if your gains before the annual allowance exceed £3,000. This reporting requirement catches many casual investors by surprise, particularly those who’ve sold, and how much they’ve received in total across multiple transactions. Keeping detailed records of all purchase and sale dates, prices, and fees helps you accurately calculate your CGT when required.
Different Types of Assets and Their Tax Treatment
Different assets attract gains tax in various ways, and knowing these distinctions helps you make informed decisions about when and what to sell.
Residential property
When you sell a buy-to-let property or second home, you need to pay gains tax on any profit, calculated after deducting purchase costs, improvement costs, and selling fees. The 60-day reporting rule for UK property means you must report and pay within two months of completion, much faster than other assets.
Stocks, shares and cryptocurrencies
For these types of assets, you pay tax on the profit, applying your annual allowance first, then paying at either 18% or 24% depending on your total income. Shares and investments bought before April 1982 are subject to special valuation rules, while those acquired through employee share schemes may be treated differently depending on the scheme type. The gains you make from cryptocurrency count as capital gains, not currency exchanges, despite many people mistakenly treating them differently.
Personal pensions and collectables
Items like jewellery, antiques, art, and classic cars only incur CGT if they’re worth more than £6,000 when you sell them. Items worth less than £6,000 are tax-free. A special “chattels rule” applies to items worth between £6,000 and £15,000, limiting the taxable gain to ensure you don’t pay disproportionate tax on modest collectables. One antique selling for £7,000 that you bought for £5,000 would only see a portion of the £2,000 gain taxed.
Business assets and rental income-generating property
Business Asset Disposal Relief (formerly Entrepreneurs’ Relief) can reduce CGT to 10% on qualifying business sales, though strict conditions apply and you must have owned the business for at least two years. Rental income itself doesn’t qualify for CGT (it’s taxed as income), but selling a rental property does. Understanding which category your asset falls into helps you estimate the tax you might face and whether there are planning opportunities to reduce your burden. If you’re selling multiple asset types in the same tax year, professional tax advice often proves worthwhile given the complexity of the calculations and the potential savings available through proper planning.
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