As a UK tax resident, your investment income, such as capital gains, dividends, and interest, is usually taxed. You are responsible for accurate and early income declaration to avoid penalties and to ensure correct tax deductions.
Understanding Investment Income
HMRC defines total investment income as “the sum of rents from UK property, interest from banks, building societies and other deposit takers, UK dividends and other forms of investment income.” This is a broad definition that covers many investments. Any profit you make from buying or selling securities, trading forex and CFDs on TradingView, and trading cryptocurrencies falls under investment income.
Profits from selling items like fine wine, gold, artworks, etc., are also subject to tax. However, there are different tax rules for each investment income category. For example, taxes on capital gains from rental income differ from those on crypto assets, depending on the circumstances.
When Do You Need to Declare Investment Income
Declaring your income depends on the type of investment income, the amount received, and your tax situation. Here are the types of income you must declare and their thresholds:
- Bonds and Gilts: If you hold bonds outside an Individual Savings Account (ISA) or Self-Invested Personal Pension (SIPP), you must declare any income from them according to HMRC guidelines.
- Dividend Income: HMRC £500 as the Dividend Allowance for the 2025/26 tax year, so you’re taxed only if your Dividend Income exceeds that amount. You must declare excess income and pay tax based on the tax band rate. The Basic, Higher, and Additional rates are 8.75%, 33.75%, and 39.35%, respectively.
- Rental Income: Income from commercial properties within the UK is subject to investment tax and should be declared.
- Overseas Investment Income: You should declare if you have investments abroad, including overseas savings accounts, stocks, dividends, real estate, and assets liable for Capital Gains Tax. You may qualify for exemptions to prevent double taxation.
- You must also file tax returns whenever HMRC requests it. As the UK’s tax authority, HMRC may request specific information that you’re bound to provide.
- You must declare investment income in the same year you realise gains. This also applies to rental income, which is declared annually. You must declare income from interests and dividends when paid and Capital Gains when you realise the profit or loss.
How to Declare Income to HMRC
Once you identify your taxable income, the next step is to send your tax returns to HMRC. You can do that in three ways: register on the official UK website to complete the SA100 tax return, request the paper tax return form called SA200, or use the Capital Gains Service (CGS). Note that you cannot download the SA200 and should only use it if HMRC sends it to you.
You’ll need to register as a self-assessment taxpayer if using the online method. Note that you must register by 5 October 2025 if you haven’t sent a tax return and need to do so.
- Go to the UK self-assessment registration and complete it, then create a user ID and password. You can sign up with your business account if you already have one.
- Answer the question prompts to specify you’re registering for Self Assessment.
- Complete the form and provide details about you and your business. These include your name (and any previous name), National Insurance number, date of birth, home address, telephone number, and email address,
- The type of work you do, etc.
HMRC will send your Unique Taxpayer Reference (UTR) within two weeks of registration, along with an activation code, which you’ll use to sign in.
How to Calculate Tax Liability and Avoid Penalties
As a self-assessment taxpayer, you must carefully calculate your taxes to avoid inaccurate reports that the HMRC will penalise. Here are a few tips to guide you:
- Add up all dividends, interests, and capital tax gains. You should have a way to track your investment income from every platform you use. Some brokers, crypto wallets, and payment systems offer built-in tools to calculate your inflows and outflows, which can help with our tax returns.
- Take note of all deductions you qualify for, including expenses related to investment management and other tax relief.
- You can also calculate your taxable income using the HMRC Capital Gains Tax tool.
- Use the online returns to make amends for any errors made while filing our returns, or write HMRC to make amends on paper.
If you’re unsure of your calculations, consult a tax expert. Studying the tax rules and changes for the tax year is the best way to understand how they affect your investments.
Get Started on Time
The deadlines for the tax return for the year ended 5 April 2025 are 31 October 2025 (paper filing) and 31 January 2026 (online filing). You have enough time to evaluate your investments and calculate taxable income before HMRC comes knocking. Contact HMRC to clarify tax issues, technical errors, and anything related to Self Assessment.