Capital Gains Tax Calculator UK (2024/25 & 2025/26)

Capital Gains Tax Calculator Breakdown

Once you’ve entered your figures, your results from the Capital Gains Tax Calculator UK will show:

• Total gain — your profit before any deductions
• Tax-free allowance — the first £3,000 of gains is exempt from CGT in 2024/25 and 2025/26
• Taxable gain — what’s left after the allowance
• CGT payable — the actual tax you owe
• Profit after tax — your real take-home gain

All figures update instantly as you type, so the Capital Gains Tax Calculator UK lets you model different scenarios before making any decision.

How Capital Gains Tax is Calculated

Capital Gains Tax is charged on the profit you make when you sell or dispose of an asset — not the total amount you receive.

Step 1 — Work out your gain
Subtract what you originally paid (plus any allowable costs, such as legal fees or improvement costs for property) from your sale price.

Gain = Selling Price − Original Cost − Allowable Expenses

Step 2 — Deduct your CGT allowance
Every individual gets an annual tax-free allowance. For 2024/25 and 2025/26, this is £3,000. Gains below this threshold are not taxed.

Step 3 — Stack gains on top of your income
This is where many people get caught out. HMRC adds your taxable gain on top of your other income to determine which tax band applies. If your salary already takes you above the basic rate threshold of £50,270, your entire gain is taxed at the higher rate.

Step 4 — Apply the correct rate
The rate depends on both your income level and the type of asset sold.

Capital Gains Tax Rates & Allowances 2024–2027

Annual Exempt Amount

Tax Year	CGT Allowance
2023/24	£6,000
2024/25	£3,000
2025/26	£3,000

The allowance has been cut significantly in recent years. If you have unused losses from previous years, now is a good time to offset them.

CGT Rates from 30 October 2024

Following the Autumn Budget 2024, CGT rates on most assets increased. Here is what applies now:

Asset Type	Basic Rate Taxpayer	Higher/Additional Rate Taxpayer
Shares, funds & ETFs	18%	24%
Crypto assets	18%	24%
Other assets	18%	24%
Residential property	18%	24%

Important for 2024/25: If you sold assets before 30 October 2024, the old rates apply — 10%/20% for most assets, and 18%/28% for residential property. Our Capital Gains Tax calculator handles this split automatically.

Example Capital Gains Tax Calculation

The Capital Gains Tax Calculator UK applies this logic automatically. Here is a worked example:

Scenario: You sell shares in 2025/26, making a £20,000 profit. Your salary is £35,000.

Step	Calculation	Amount
Total gain	—	£20,000
Deduct CGT allowance	£20,000 − £3,000	£17,000
Taxable income above personal allowance	£35,000 − £12,570	£22,430
Remaining basic rate band	£37,700 − £22,430	£15,270
Gain taxed at 18% (basic rate)	£15,270 × 18%	£2,748.60
Gain taxed at 24% (higher rate)	£1,730 × 24%	£415.20
Total CGT payable		£3,163.80
Profit after tax	£20,000 − £3,163.80	£16,836.20

Because your salary uses up most of the basic rate band, only a small portion of your gain qualifies for the lower 18% rate — the rest is taxed at 24%.

Ways to Reduce Your Capital Gains Tax Bill

You don’t have to pay more than you need to. Here are the most effective and HMRC-approved strategies:

• Use your annual allowance every year The £3,000 exemption cannot be carried forward. If you don’t use it, you lose it. Consider realising gains each tax year to make the most of it.
• Offset capital losses If you’ve made losses on other assets in the same tax year — or in previous years — you can deduct them from your gains before calculating tax. Losses must be reported to HMRC to be used, even if no tax is due.
• Transfer assets to a spouse or civil partner Transfers between spouses and civil partners are exempt from CGT. This means you can effectively double your allowance by transferring part of an asset before selling, making use of both partners’ exemptions and potentially lower tax rates.
• Invest through an ISA Gains made inside a Stocks and Shares ISA are completely free from CGT, no matter how large. Moving assets into an ISA (known as a Bed and ISA) uses your annual subscription allowance but shelters future growth permanently.
• Use pension contributions strategically Pension contributions reduce your adjusted net income, which can move your taxable income down a band — potentially pushing some or all of your capital gains into the basic rate band.

When and How to Pay Capital Gains Tax

For most assets — Self Assessment

If you need to pay CGT on shares, crypto, or other assets, you report and pay through your Self Assessment tax return. The deadline is 31 January following the end of the tax year. So for gains made in 2024/25 (year ending 5 April 2025), you must file and pay by 31 January 2026.

For residential property — 60-day rule

If you sell a UK residential property and CGT is due, you must report and pay within 60 days of completion — not at the end of the tax year. Missing this deadline results in automatic penalties and interest.

Don’t assume you only need to report if you owe tax

You may still need to complete a Self Assessment return if your total proceeds exceeded £50,000, even if your gain is below the allowance.

Before making any decisions, use the Capital Gains Tax Calculator UK to estimate your position, then speak to a qualified adviser for tailored advice.

Frequently Asked Questions

This content is for informational purposes only and does not constitute tax advice. Tax rules can change — always consult a qualified tax adviser for guidance specific to your situation.