Whether you are a seasoned investor or just beginning to build a shared portfolio, understanding tax on shares is more than just good practice, it’s essential for protecting your returns.
Many people focus entirely on choosing the right stocks but forget to factor in the tax consequences that come with selling or transferring them. This can lead to unexpected tax bills and significantly impacts your net profit.
This guide will help you understand:
- What Is Capital Gains Tax on Shares
- When Do You Pay Tax on Shares
- How Capital Gains on Shares Are Calculated
- Reporting and Paying Capital Gains Tax on Shares
- Shares That May Be Exempt from Capital Gains Tax
- Capital Losses and How They Reduce Tax on Shares
What Is Capital Gains Tax on Shares?
Capital Gains Tax (GCT) refers to the tax applicable on the profit or gain you make when disposing off an asset that has increased in value. When it comes to shares, the gain is calculated as the difference between what you paid for them and what you are receiving when selling or transferring them.
It is important to understand the difference between dividend income and capital gains. Dividends are payments made by the company to its shareholders from company profits, which is taxed separately under income tax rules.
Capital gains on shares refers to the increase in value of shares themselves at the time of disposal. You can own shares for decades without having to pay any CGT, as it only becomes necessary upon disposal.
When Do You Pay Tax on Shares?
Capital Gains Tax can arise in several situations beyond a straightforward sale. Such a tax liability can occur in the following scenarios:
- Selling shares at a profit: if you sell shares at a gain, you have to pay tax on it.
- Gifting Shares: when you gift your shares to someone other than your spouse/civil partner, it is treated as a disposal, making it taxable.
- Transferring Shares between individuals or entities: Moving shares to a trust, a company or another individual’s ownership can trigger CGT depending on the relationship and circumstances.
- Inheritance of shares & subsequent disposal: inheriting Shares is tax-free, but selling those inherited shares later, can trigger tax. This tax is applied to any gain made between the sale of shares and revaluation at the time of the original owner’s death.
How Capital Gains on Shares Are Calculated
To find out how much tax you owe, you first need to work out your capital gain using this formula:
Sale proceeds – Purchase cost (– Allowable costs) = Chargeable gain
You can also deduct certain allowable costs from your total gain, which include stockbroker fees, commission charges and any stamp duty reserve tax (0.5%) which is paid when you bought the shares.
Calculating Gains When You Have Multiple Purchases
Calculating capital gain on shares can get more complicated if you have bought shares in the same company on multiple dates, and at different prices. HMRC does not allow you to simply choose the most expensive purchase to reduce your tax bill. Instead, you must follow a strict order of three matching rules, as explained below.
1. Same-Day Rule
If you buy and sell shares of the same company on the same day, these shares are matched against each other first.
Example-1
You buy 100 shares today at £15 each and sell 100 shares today at£17 each. These are matched together, which means your gain would be:
£17(Selling Price) – £15 (Buying Price) = £2 Gain per share
2. 30-Day Rule (Bed & Breakfast Rule)
If you sell shares and buy shares in the same company back within 30 days of selling, the repurchased shares are matched against the sale first.
Example-2
January: You buy 100 shares for £10 each.
May 3rd: You sell 50 shares for £20 each.
May 29th: You buy 50 shares for £21 each.
Since you bought back the shares, within 30 days of selling, HMRC will match your 3rd May sale with your 29th May purchase. Your gain is calculated as:
£20 (Selling Price) – £21 (buying price) =£1 Loss per share
Your original 50 unsold shares will remain in the pool at their original cost of £10 each.
3. Section 104 Pool (Average Cost)
All the same class shares that are not caught by the same-day rule or the 30-day rule are pooled together. The total cost of the pool is divided by the number of shares to give an average cost per share, which is used to calculate the gain or loss on any future sale.
Example-3
January 2025: 100 shares bought at £10 each (Cost = £1000)
June 2025: 100 shares bought at £15 each (Cost = £1,500)
March 2026: 50 shares bought at £20 each (Cost = £1000)
Average cost per share: £3,500 ÷ 250 shares = £14 per share
When you sell any of these shares, you will use this average cost of £14 to calculate your gain.
Annual CGT Allowance
Once your net gain is calculated, the next step is to apply the annual capital gains tax allowance. For the tax year 2026/27, this allowance stands at £3,000. Any gains exceeding this annual allowance are considered taxable.
If your shares are jointly owned with a spouse or a civil partner, you each get your own £3,000 allowance. You could potentially double your tax-free gains to £6,000.
Reporting and Paying Capital Gains Tax on Shares
If you have a taxable gain above the annual exempt amount, you are required to report it to HMRC.
CGT Tax Rates on Shares
The rate of Capital Gains Tax you pay depends on your income band. Basic-rate taxpayers are charged 18%, whereas Higher-ratetaxpayers have to pay 24% in CGT.
If your total taxable income plus your capital gain pushes you into a higher band, you pay 18% on the portion that falls within the basic rate band and 24% on the rest.
How and When to Report
For most individuals, this is done via Self-Assessment Tax Return. The reporting deadline is 31st January following the end of the relevant tax year. HMRC’s Capital Gains Tax real-time service also allows you to report and pay tax outside of Self-Assessment if you do not usually complete a tax return.
Shares That May Be Exempt from Capital Gains Tax
There are certain shares that do not trigger a tax liability. These include:
ISA-held Shares: Shares held within an Individual Savings Allowance are entirely free from Capital Gains Tax, regardless of how much profit you make on disposal.
Employee share schemes: Shares acquired under certain HMRC-approved schemes such as Enterprise Management Incentives (EMI) andShare Incentive Plans (SIPs) may qualify for exemption and relief, provided the relevant conditions are met.
Capital Losses and How They Reduce Tax on Shares
If you sell shares at a price below their original purchase cost, this results in a capital loss.
Capital losses are a valuable tool for reducing your overall CGT bill. You can use your losses to offset gains, provided they are in the same tax year.
Example – 4
You make £6,000 gain on one holding but a £2,000 loss on another. Only £4,000 would be subject to CGT, before applying the annual allowance.
If your losses exceed your gains in a given tax year, they can be carried forward indefinitely to offset against any future gains.
You must keep accurate records and actively report your losses and gains to HMRC in a timely manner. Strategically realising gains/losses before the tax year ends can be a powerful tax-planning tool.
Conclusion
Capital gains tax on shares is a complex but manageable aspect of investing, provided you understand the rules and plan accordingly. From knowing which disposals trigger tax, to using losses effectively and taking full advantage of available exemptions, a structured approach can make a meaningful difference to the tax you pay over time.
If you are unsure how capital gains tax applies to your shares or want to plan future disposals more efficiently, Heighten Accountants can help you assess your position and ensure everything is reported correctly.
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