UK Tax on Investments: CGT, Dividend Tax and ISA Rules

The UK Tax System for Investors

UK investors face two main taxes on investment returns outside of tax-sheltered accounts: Capital Gains Tax on profits from selling investments, and Dividend Tax on income received from shares and funds. Understanding these taxes — and using the available allowances and shelters effectively — can make a significant difference to your long-term investment returns.

Capital Gains Tax (CGT) for UK Investors

When you sell an investment for more than you paid for it, the profit is a capital gain. CGT is charged on gains above the annual CGT allowance — currently £3,000 for 2024/25, reduced from £12,300 in 2022/23. For basic rate taxpayers, CGT on investments is charged at 18 per cent. For higher and additional rate taxpayers, the rate is 24 per cent. CGT does not apply within an ISA or SIPP — gains there are completely tax-free.

Losses can be offset against gains in the same tax year, or carried forward to future years. If you have made losses on some investments, you can use these to reduce your taxable gains. This practice of crystallising losses to offset gains is sometimes called tax-loss harvesting.

Dividend Tax

Dividends received from shares and funds are taxed as income above the annual Dividend Allowance — currently £500 for 2024/25, reduced from £2,000 as recently as 2022/23. Above this allowance, dividends are taxed at 8.75 per cent for basic rate taxpayers, 33.75 per cent for higher rate taxpayers, and 39.35 per cent for additional rate taxpayers. Dividends received within an ISA are completely tax-free regardless of amount.

Using the ISA to Eliminate Investment Tax

The Stocks and Shares ISA is the most powerful tool available to UK investors for eliminating investment tax. Up to £20,000 per person per year can be invested in an ISA. All capital gains, dividends, and interest within the ISA are completely free from UK tax, with no reporting required. Over a lifetime of investing, the tax saving from consistent ISA use can be enormous — particularly as the CGT and Dividend Tax allowances have been cut repeatedly in recent years.

The SIPP: Tax Relief on the Way In

Pensions including SIPPs offer tax relief on contributions rather than tax-free growth and income as with the ISA. Basic rate taxpayers get 20 per cent tax relief — a £80 contribution becomes £100. Higher rate taxpayers can claim an additional 20 per cent through self-assessment, making a £100 contribution effectively cost £60. Income within a SIPP grows tax-free but is taxed as income when withdrawn in retirement — though 25 per cent can be taken as a tax-free lump sum.

Reporting Requirements

If you have investment income or gains outside an ISA or SIPP, you may need to complete a self-assessment tax return. This is required if your total untaxed income exceeds £2,500, your CGT liability exceeds your annual allowance, your dividend income exceeds the £500 allowance, or you have other untaxed income. ISA and SIPP income does not need to be reported. Keeping clear records of all investment transactions — purchase price, sale price, dates, and any associated costs — is important for accurate CGT calculations.

Bed and ISA

If you hold investments in a taxable general investment account and want to move them into an ISA, you cannot simply transfer them. You must sell the investments in the GIA and repurchase them in your ISA — a process called Bed and ISA. This may trigger a CGT liability if you have gains, though careful timing around your annual CGT allowance and any available losses can minimise the tax cost. The long-term benefit of sheltering the investments in an ISA typically outweighs the one-off CGT cost.