Capital Gains Tax Calculator UK - Calculate CGT on Property & Shares

Our capital gains tax calculator UK helps you quickly calculate capital gains tax on property, shares, and other assets for 2026/27. Whether you're selling a second property, disposing of shares, or realizing gains on cryptocurrency, this free CGT calculator provides instant, accurate calculations using current HMRC rates and the latest capital gains allowance.

Understanding how to calculate capital gains tax is essential for anyone selling assets in the UK. Capital gains tax (CGT) is a tax on the profit when you sell (or 'dispose of') something that has increased in value. Unlike income tax, you only pay CGT on the gain itself, not the entire amount you receive. Our capital gains tax calculator UK tool makes it simple to work out exactly how much tax you'll owe.

For 2026/27, the annual capital gains allowance is £3,000 (reduced from £6,000 in 2023/24). This means you can make gains of up to £3,000 tax-free each year. Any gains above this threshold are subject to CGT at rates ranging from 10% to 24% depending on the asset type and your income tax band. Use our calculate capital gains tax UK tool to see your exact liability.

Who Should Use This Capital Gains Tax Calculator?

This calculator is designed for anyone disposing of assets that have increased in value. You might be selling a buy-to-let property or second home and need to estimate your CGT bill before completion. Perhaps you're cashing in shares or investment funds outside of an ISA and want to know if you'll exceed the annual allowance. Maybe you've inherited property or investments and are considering selling.

The calculator handles the two main asset categories: residential property (which attracts higher CGT rates of 18% or 24%) and other assets like shares, commercial property, and personal possessions (taxed at 10% or 20%). Your main residence is exempt from CGT under Private Residence Relief, so this calculator isn't needed if you're selling your only home.

If you're disposing of business assets and potentially eligible for Business Asset Disposal Relief (formerly Entrepreneurs' Relief), which reduces CGT to 10% on qualifying disposals up to £1 million lifetime, you should consult an accountant. Similarly, if you've made losses on other assets in the same tax year or carried forward losses from previous years, the calculation becomes more complex and professional advice is recommended.

Understanding the Capital Gains Tax Calculation: Complete Methodology

Our calculator follows HMRC's official methodology for calculating Capital Gains Tax. Here's exactly how your CGT liability is determined, broken down into clear steps you can verify yourself.

Step 1: Calculate Your Gross Gain
Start with the sale price (disposal proceeds) of your asset. From this, subtract the original purchase price (acquisition cost). This gives you the headline gain, but we're not finished yet. You can also deduct all the costs associated with buying and selling the asset.

For property, these costs typically include solicitor fees, estate agent fees, stamp duty you paid when buying, and survey costs. For shares, you can deduct stockbroker commission and platform fees. These costs can significantly reduce your taxable gain. A property sale with £8,000 in combined buying and selling costs reduces your CGT liability by £1,920 if you're a higher-rate taxpayer (£8,000 x 24%).

Step 2: Deduct Improvement Costs
You can also deduct money spent on improvements that added lasting value to the asset. For property, this includes extensions, loft conversions, new kitchens or bathrooms. Routine repairs and maintenance don't count - only capital improvements that enhanced the asset's value permanently.

This distinction matters. Repainting a property before sale is maintenance (not deductible). Installing a new bathroom suite is an improvement (deductible). If you're unsure whether a cost qualifies, HMRC's test is whether it put the asset into a better state than when you bought it, rather than simply maintaining its existing condition.

Step 3: Apply the Annual Exemption
Every UK taxpayer gets a £3,000 annual capital gains allowance for 2026/27. This is the amount of gains you can realize each tax year completely tax-free. The allowance applies to your total gains across all disposals in the tax year - it's not £3,000 per asset.

If you're married or in a civil partnership, each partner gets their own £3,000 allowance. This means transferring assets between spouses before sale can be a powerful planning tool. If you own a second property jointly, you could each use your allowance, effectively getting £6,000 tax-free between you.

Step 4: Determine Your Tax Rate
The CGT rate you pay depends on two factors: what type of asset you're selling and which income tax band you fall into. For residential property, basic-rate taxpayers pay 18% and higher or additional-rate taxpayers pay 24%. For other assets (shares, commercial property, collectibles), the rates are 10% and 20% respectively.

Here's where it gets slightly complicated: your tax band is determined by your income plus your capital gains. If you're a basic-rate taxpayer earning £40,000 but you make a £30,000 capital gain, part of that gain will be taxed at the basic rate and part at the higher rate. Our calculator handles this calculation automatically, working out exactly where you cross into the higher-rate threshold.

How to Use This Calculator: Field-by-Field Guide

Getting accurate CGT calculations requires entering the right information. Here's what each field means and how to complete it correctly.

Sale Price: Enter the actual amount you received (or will receive) from selling the asset. For property, this is the price agreed in the sale contract. For shares, it's the total proceeds you received from the sale, before any broker fees are deducted. Don't enter the price after costs - you'll deduct those separately.

Purchase Price: This is what you originally paid for the asset. For property, use the price on the purchase contract. For inherited assets, use the market value on the date of death - you can find this on the probate valuation. For gifted assets, use the market value when you received the gift. If you can't find the exact purchase price, HMRC may accept a professional valuation.

Improvement Costs: Enter the total amount spent on capital improvements (not maintenance). Only include costs that added lasting value. Keep receipts and invoices to support these deductions in case HMRC queries your calculation. If you're unsure whether a cost qualifies, err on the side of caution or seek professional advice.

Selling Costs: Include all costs directly related to selling the asset: estate agent fees, solicitor fees, advertising costs. For shares, include broker commission and platform fees. These costs are fully deductible and can substantially reduce your CGT bill.

Annual Income: Enter your total taxable income for the year (salary, rental income, dividends, etc.). This determines whether you're a basic or higher-rate taxpayer for CGT purposes. The calculator uses this to apply the correct tax rate and to calculate if any of your gain pushes you into a higher tax bracket.

Asset Type: Select whether you're selling residential property or other assets (shares, commercial property, etc.). This is crucial because residential property is taxed at higher rates (18%/24%) compared to other assets (10%/20%).

Selling an Inherited Property

When you inherit property, your CGT calculation starts from the property's value at the date of death, not what the deceased originally paid. If your father bought a house for £100,000 in 1995 and it was valued at £300,000 when he died in 2023, your purchase price for CGT purposes is £300,000. If you sell it in 2025 for £320,000, your gain is only £20,000 (less costs), not £220,000. This is called probate value uplift and significantly reduces CGT on inherited assets.

Selling Your Second Property

Buy-to-let investors face the highest CGT rates. If you bought a rental property for £180,000, spent £20,000 on a loft conversion, and sell it for £280,000 with £10,000 in selling costs, your gain is £70,000. After the £3,000 allowance, you'll pay CGT on £67,000. As a higher-rate taxpayer, that's £16,080 in tax (24%). Spreading the sale across two tax years by exchanging in one year and completing in the next won't work, HMRC uses the exchange date for CGT purposes.

Transferring Assets Between Spouses

Married couples and civil partners can transfer assets between themselves without triggering CGT. This is powerful for tax planning. If you own shares worth £100,000 with a £50,000 gain and want to sell them, you could transfer half to your spouse first. You each then have a £25,000 gain and can use your £3,000 allowances, saving up to £1,200 in tax. The transfer must happen before the sale, and you must be living together for this exemption to apply.

Cryptocurrency Disposals

Every cryptocurrency transaction is potentially a taxable disposal. Selling crypto for pounds, exchanging one cryptocurrency for another, using crypto to buy goods or services, or gifting crypto all trigger CGT. With the £3,000 allowance reduced from £12,300 just two years ago, many people who thought their crypto gains were tax-free now owe tax. HMRC can request transaction data from UK exchanges, so ensure you calculate your liability correctly using our CGT calculator.

This calculator provides accurate estimates for straightforward CGT calculations on single asset disposals. However, it doesn't account for every possible relief, exemption, or complex scenario. The calculator assumes you're a UK resident disposing of UK assets with no previous capital losses to carry forward.

More complex situations require professional advice. If you're disposing of business assets and may qualify for Business Asset Disposal Relief, selling a property you've used partly as a home and partly for business, disposing of foreign assets or property abroad, claiming Private Residence Relief for a property you've sometimes let out, or have losses from previous years to offset, consult a qualified tax adviser or accountant.

The calculator also doesn't handle complex share transactions like the bed and breakfast rule (selling and repurchasing shares within 30 days), Section 104 holding calculations for shares bought at different times, or share reorganizations and takeovers. For these situations, HMRC's own Capital Gains Tax summary or a tax professional should be consulted.

About This Calculator

This Capital Gains Tax calculator is maintained by Mia Carragher, who writes practical guidance to help UK taxpayers navigate complex tax situations. The calculations are based on HMRC's official CGT rates and allowances for the 2026/27 tax year, confirmed in the Spring Budget.

We update this calculator immediately after each Budget to reflect any changes to CGT rates, allowances, or thresholds. The methodology follows HMRC's official guidance on calculating capital gains, including the correct treatment of allowable costs, improvement expenditure, and the annual exemption. The calculator has been verified against HMRC's own CGT calculations and real-world scenarios from hundreds of users.

This calculator is for guidance only and should not be considered financial or tax advice. Capital Gains Tax can be complex, and professional advice is recommended for substantial disposals or complicated situations. For property sales, remember the 60-day reporting rule - you must report and pay your CGT within 60 days of completion through HMRC's UK Property Reporting Service. Late reporting carries automatic penalties starting at £100.