UK Capital Gains Tax Calculator 2025/26

💷 UK Capital Gains Tax Calculator 2025/26

Calculate tax on property, shares, crypto, and other assets

📅 Tax Year: 6 April 2025 - 5 April 2026 | AEA: £3,000
🏠 Asset Type (determines tax rate)
💳 Your Income Tax Band

UK Capital Gains Tax Calculator: What It Is, How It Works, and Why You Actually Need One

If you’ve ever sold a property, cashed in some shares, or offloaded a business asset and then stared blankly at your tax return wondering what you owe HMRC — you’re not alone. Capital gains tax is one of those things most people don’t think about until they’re suddenly sitting on a profit and someone mentions a tax bill. That’s where a UK Capital Gains Tax Calculator becomes genuinely useful.

This guide walks you through exactly what it does, how to use one step by step, and what the numbers actually mean for your situation.

What Is a UK Capital Gains Tax Calculator?

A UK Capital Gains Tax Calculator is a tool that estimates how much Capital Gains Tax (CGT) you owe after selling or disposing of an asset — property, shares, business assets, or personal possessions worth over £6,000.

You enter a few key figures — your gain, your income, your allowances — and it calculates your approximate CGT liability based on the current HMRC rates and thresholds.

It doesn’t replace a tax adviser. But it gives you a clear starting point before you file a return or pick up the phone.

Why Does Capital Gains Tax Even Matter?

Here’s the thing: CGT catches a lot of people off-guard. You buy a buy-to-let flat for £180,000, sell it a decade later for £280,000 — congratulations, you’ve made £100,000. But you don’t keep all of it.

HMRC wants a share of that gain. And depending on your total income and the type of asset you’ve sold, the rate can be anywhere from 18% to 24% on property, or 10% to 20% on shares and other assets (as of the 2025/26 tax year).

Miss it, and you could face penalties. Get ahead of it with a calculator, and there are no surprises.

Related reading: UK Stamp Duty Calculator — First-Time Buyer 2025

How Capital Gains Tax Is Calculated in the UK — The Formula

Before using any calculator, it helps to understand what’s going on under the hood. The basic formula is:

Capital Gain = Sale Price – Purchase Price – Allowable Costs

Then:

Taxable Gain = Capital Gain – Annual CGT Allowance

And finally:

CGT Owed = Taxable Gain x Applicable Tax Rate

That’s it. Three steps. The complexity comes from the details — what counts as an allowable cost, what your income is, whether you’re a basic or higher-rate taxpayer, and what type of asset you sold.

The Annual CGT Allowance (2025/26)

Every individual gets a tax-free allowance before CGT kicks in. For the 2025/26 tax year, that allowance is £3,000.

Yes — it’s gone down significantly from the £12,300 it was just a few years ago. If you’re planning any disposals, this lower allowance means more of your gain is likely to be taxable now.

Couples who jointly own assets can each use their own allowance, effectively doubling it to £6,000 between them. Worth knowing before you dismiss the maths as someone else’s problem.

Current UK CGT Rates (2025/26)

The rate you pay depends on two things: your total taxable income and the type of asset sold.

For residential property (excluding your main home, which is usually exempt under Private Residence Relief):

  • Basic-rate taxpayers: 18%
  • Higher or additional-rate taxpayers: 24%

For other assets — shares, business assets, most personal possessions:

  • Basic-rate taxpayers: 10%
  • Higher or additional-rate taxpayers: 20%

Your income matters here. If your total income plus your taxable gain pushes you into the higher-rate band, the portion that sits above the basic-rate threshold is taxed at the higher rate. A calculator handles this automatically once you input your annual income.

How to Use a UK Capital Gains Tax Calculator — Step by Step

Let’s walk through this with a real example.

Imagine you sold a buy-to-let property in Leeds. You bought it in 2015 for £165,000 and sold it in 2025 for £245,000. Your income from your job this year is £32,000. You spent £5,000 on estate agent fees and solicitor costs when selling.

Step 1: Calculate your gain

Sale price: £245,000 Purchase price: £165,000 Selling costs: £5,000

Gain = £245,000 – £165,000 – £5,000 = £75,000

Step 2: Subtract the CGT allowance

Taxable gain = £75,000 – £3,000 = £72,000

Step 3: Work out your tax band

Your income is £32,000. The basic-rate income tax band for 2025/26 goes up to £50,270. So you have £18,270 of remaining basic-rate band before hitting the higher-rate threshold (£50,270 – £32,000 = £18,270).

Step 4: Apply the rates

First £18,270 of your gain (at the basic rate): 18% = £3,288.60 Remaining £53,730 (above the threshold, at higher rate): 24% = £12,895.20

Total CGT owed: approximately £16,183.80

You’d enter all of this into a UK Capital Gains Tax Calculator and get this result in seconds — without having to do the band-splitting manually.

What Counts as an Allowable Cost?

This is where people often undercount and end up overpaying. Allowable costs you can deduct from your gain include:

  • The original purchase price
  • Solicitor and conveyancing fees (buying and selling)
  • Estate agent fees
  • Stamp duty paid when purchasing
  • Capital improvements to the property (not maintenance — a new kitchen counts, repainting doesn’t)
  • Survey costs

What doesn’t count: mortgage interest, insurance, regular maintenance. Those are income expenses, not capital ones.

Getting your allowable costs right can meaningfully reduce your taxable gain. A decent UK Capital Gains Tax Calculator will let you input these itemised costs rather than just lumping everything together.

Special Reliefs That Reduce Your CGT

A few reliefs are worth knowing about before you calculate anything.

Private Residence Relief (PRR): If the property was your main home for any period, you may qualify for full or partial relief. The final 9 months of ownership always qualify, even if you’ve moved out. For properties you’ve lived in and then rented, this gets more complex — but it can substantially reduce your bill.

Business Asset Disposal Relief (formerly Entrepreneurs’ Relief): If you’re selling a qualifying business or business asset, you may pay just 10% CGT on the first £1 million of lifetime gains.

Losses: If you’ve made a capital loss elsewhere — sold shares at a loss, for instance — you can offset that loss against your gain before calculating tax. Losses in the same tax year are applied first, then carried-forward losses.

A calculator won’t always apply these reliefs for you automatically, but knowing they exist means you know what to discuss with an accountant if they apply.

Benefits of Using a UK Capital Gains Tax Calculator

The obvious one is speed. Instead of working through HMRC’s own guidance (which runs to dozens of pages) you get a ballpark figure in under two minutes.

But there are subtler benefits too. It helps you plan ahead. If you’re considering selling in this tax year versus next, running the numbers both ways shows you whether waiting makes financial sense. It’s also useful for understanding whether a loss on one asset can sensibly offset a gain on another — something worth timing carefully if you have flexibility.

For anyone managing a small portfolio of properties or investments, checking the compound interest calculator alongside a CGT calculator gives you a fuller picture of your net returns over time.

Limitations to Keep in Mind

A UK Capital Gains Tax Calculator gives you an estimate, not a final tax bill. A few things it typically won’t account for:

  • Complex ownership structures (trusts, partnerships)
  • Non-UK residents selling UK property (different rules apply)
  • Assets transferred between spouses or civil partners (generally exempt but affects the recipient’s base cost)
  • Interaction with other reliefs specific to your circumstances

If your situation is straightforward — you sold shares or a second property, you know your income, you have your purchase and sale figures — a calculator is genuinely reliable for planning purposes. For anything involving business assets, PRR calculations, or multiple disposals in one year, it’s worth cross-checking with a tax professional.

Also worth noting: CGT rates and allowances change. The 2025/26 figures apply now, but future budgets may adjust them. Always verify the current thresholds against HMRC’s official guidance before you file.

When Do You Need to Report and Pay CGT?

Two things to know:

For property sales, you must report and pay CGT within 60 days of completion using HMRC’s online service. This is a firm deadline.

For other assets (shares, personal possessions), CGT is reported through your Self Assessment tax return for the relevant tax year, with payment due by 31 January following the end of that tax year.

Missing the property deadline in particular carries an immediate penalty, so getting ahead with a calculator before you complete a sale is actually important practical timing — not just useful, but necessary.

Related UK Financial Calculators

If you’re working through UK tax and financial planning more broadly, these tools might also help:

Browse all UK Calculators on YourCalculatorHub.

FAQs About UK Capital Gains Tax Calculator

What is the CGT allowance for 2025/26? The annual CGT-exempt amount is £3,000 per individual for the 2025/26 tax year.

Do I pay CGT when I sell my main home? Usually not. Private Residence Relief typically exempts your primary residence from CGT. But if you’ve let it out or it has grounds over half a hectare, partial CGT may apply.

How does my income affect CGT? Your income determines which tax band your gain falls into. If adding your taxable gain to your income pushes you above £50,270 (the basic/higher-rate threshold), the portion above that level is taxed at the higher CGT rate.

Can I offset losses against gains? Yes. Capital losses from other disposals in the same tax year can be used to reduce your total taxable gain. Unused losses can also be carried forward to future years if registered with HMRC.

Is a CGT calculator accurate enough to use for HMRC reporting? Use it for planning and estimation. For your actual tax return, verify figures against HMRC’s official tools or speak with a qualified accountant.

What is the deadline for reporting CGT on property? 60 days from the date of completion on a UK residential property sale.

A Final Thought

Capital gains tax doesn’t have to feel like a guessing game. Knowing your numbers ahead of time — whether you’re selling a rental property, clearing a share portfolio, or passing on business assets — means you’re in control rather than reacting. A UK Capital Gains Tax Calculator is genuinely one of the more useful tools you can reach for early in that process.

Have you recently sold an asset and been surprised by your CGT bill? Or discovered a relief that significantly reduced what you owed? It’s more common than you’d think — and the details matter more than most people realise until they’re in it.

Disclaimer

The information provided in this article is for general informational and educational purposes only. It does not constitute financial, tax, or legal advice. Capital Gains Tax rules, rates, and allowances change frequently and may vary based on individual circumstances. Always consult a qualified tax adviser or accountant before making financial decisions. For official and up-to-date guidance, refer to HMRC’s Capital Gains Tax pages. YourCalculatorHub accepts no liability for decisions made based on the content of this article.

About the Author / Editorial Note

This article was written by the editorial team at YourCalculatorHub, a UK-focused financial tools and calculator resource. Our team researches and updates content regularly to reflect current HMRC thresholds, tax year changes, and UK financial regulations. We do not provide personalised financial advice. All calculators and articles are intended as starting-point resources to help you ask better questions — of your numbers and your advisers. For feedback or corrections, visit our Contact Us page.

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