Self-assessment tax penalties

by Aitch, posted in Income Tax

If you are required to complete a self-assessment tax return, HMRC may charge penalties if you miss the deadline for making a filing or payment. 

There are also penalties if you fail to register on time for self-assessment. If you register late and do not pay your tax bill by the required deadline, you may receive a ‘failure to notify’ penalty. This is calculated based on the amount of tax still outstanding and is usually issued within 12 months of HMRC receiving your return.

If you submit your tax return after the deadline, you will typically receive an initial £100 penalty. This is followed by daily penalties of £10 per day after three months (up to £900), and further charges at six and twelve months based on a percentage of the tax due or a fixed amount, whichever is higher.

If you pay your tax late, additional penalties of 5% of the unpaid tax may be charged after 30 days, six months and twelve months. In addition, you will also be charged interest on the outstanding balance until it is paid.

Penalties must usually be paid within 30 days of the penalty notice date, and failure to do so may result in further enforcement action. If you believe a penalty has been issued incorrectly, you can appeal where you have a reasonable excuse, and HMRC will consider your circumstances before deciding whether to cancel or reduce penalties charged.

Source:HM Revenue & Customs | 08-06-2026
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Aitch
I'm Aitch, the Founder and CEO of CIGMA Accounting Ltd. As a Chartered Management Accountant and as a CIMA member, I've spent more than 16 years helping businesses, entrepreneurs, landlords, and individuals with tax planning, accounting, and HMRC compliance. As a chartered accountant in London, I'm passionate about making complex tax matters easier to understand and helping clients make confident financial decisions. Over the years, I've advised start-ups, SMEs, established companies, and high-net-worth individuals across a wide range of tax and accounting matters. My expertise includes Corporation Tax, Self-Assessment, Capital Gains Tax, Inheritance Tax planning, R&D tax relief, capital allowances, international tax, and resolving complex HMRC compliance issues. Whether clients need a business accountant, tax accountant, or strategic tax advisor, my focus is always on delivering practical advice that creates long-term value. One of my specialist areas is Making Tax Digital (MTD). I've worked extensively with businesses preparing HMRC's digital reporting requirements, helping them move to cloud accounting, improve financial processes, and adopt technology that makes compliance more efficient. I regularly speak at Making Tax Digital roadshows, industry events, and educational sessions in collaboration with Zoho Books, sharing practical insights into digital accounting, tax legislation, and the future of the profession. Many business owners looking for the best accounting firm in London are not simply searching for an accountant they're looking for trusted advice, responsive support, and long-term value. That's the approach I've taken in building CIGMA Accounting. My team and I work closely with businesses across London and the UK, providing accounting services, tax advisory, bookkeeping, payroll, VAT, company accounts, and strategic tax planning tailored to each client's goals. Through this website, I share practical guidance on UK taxation, Making Tax Digital, HMRC updates, Corporation Tax, Self-Assessment, and business finance. My aim is to provide reliable, straightforward information that helps business owners understand changing regulations, reduce compliance risks, and make informed financial decisions with confidence.
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