There is an online tool, developed by HMRC, that allows taxpayers to check if they need to notify HMRC about additional income. The online tool can be found at www.gov.uk/check-additional-income-tax.

You are required to submit a self-assessment return if any of the following apply:

  • you were self-employed as a ‘sole trader’ and earned more than £1,000 (before taking off anything you can claim tax relief on);
  • you were a partner in a business partnership;
  • you had a total taxable income of more than £150,000 in 2023-24 (£100,000 in 2022-23);
  • you had to pay Capital Gains Tax when you sold or ‘disposed of’ something that increased in value; or
  • you had to pay the High Income Child Benefit Charge.

You may also need to send a tax return if you have any untaxed income, such as:

  • money from renting out a property;
  • tips and commission;
  • income from savings, investments and dividends; or
  • foreign income.

There could be other reasons why you may be required to register for self-assessment and therefore using HMRC’s online tool can help you check if you are required to submit a return.

Source:HM Revenue & Customs | 03-06-2024

If you’re unsure whether additional income means you need to register for Self‑Assessment or submit a tax return, getting professional advice early can help you stay compliant and avoid penalties. At CIGMA Accounting, we regularly support contractors, online businesses, landlords, and limited companies, helping individuals understand when untaxed income must be declared and how to meet HMRC Self‑Assessment obligations correctly.

Our experienced accountants support clients through our London offices in Farringdon and Hammersmith, as well as surrounding areas including Moorgate, Liverpool Street, Brook Green, and Ravenscourt Park, providing clear guidance on additional income reporting, Self‑Assessment registration, and ongoing compliance.

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CIGMA Accounting
CIGMA Accounting Ltd is a forward-thinking accounting and tax firm based in London, dedicated to delivering high-quality compliance, tax planning, and business advisory services to entrepreneurs, landlords, and growing SMEs. With offices in Wimbledon and Farringdon, we combine local expertise with a tech-driven approach to simplify accounting. Our services include corporation tax filing, VAT compliance, HMRC investigation support, R&D tax credit claims, capital allowances optimisation, and bookkeeping automation. What sets CIGMA apart is our ability to blend traditional accounting rigour with AI-powered systems that reduce errors, save time, and provide real-time financial insights. Our team ensures that every client - from startups to high-net-worth individuals - receives a bespoke solution aligned with their growth goals. Whether you need strategic tax planning, help with HMRC disclosures, or a full outsourced finance function, CIGMA Accounting delivers clarity, compliance, and confidence.
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