Self Assessment 2021–22: Tax Return and Payment Deadlines Explained

This guidance is for taxpayers with outstanding or late 2021–22 Self Assessment obligations who need to understand whether the relevant deadlines have already passed and what that means now.

Although the 2021–22 tax year has ended, missed filing or payment deadlines can still have consequences. Understanding what deadlines applied — and what action is still required — is important to limit penalties, interest, and further HMRC action.

What Happens If the 2021–22 Deadlines Were Missed

If a 2021–22 Self Assessment tax return was filed late, HMRC will normally charge late filing penalties, starting with an automatic fixed penalty. Where tax was also paid late, late payment interest and additional penalties may apply. A situation where timely self assessment advice in London can help clarify what penalties apply and whether any relief is available.

These charges do not stop automatically. Interest can continue to accrue, and unpaid balances may lead to further HMRC compliance or enforcement action if left unresolved.

Check Whether You Missed the 2021–22 Deadlines

In Practice – Why Old Deadlines Still Matter

In practice, we often see taxpayers assume that once a tax year has passed, deadlines are no longer relevant. In reality, HMRC penalties and interest can continue long after the original deadline, particularly where returns or payments remain outstanding an issue a tax specialist in London regularly helps clients address.

For tailored support, speak to experienced accountants in London who regularly assist taxpayers with overdue Self Assessment returns and historic tax issues. Our local team can help you understand what action is still required and how to deal with HMRC.

Find out more about our accounting support in London

HMRC sets out Self Assessment filing and payment deadlines, along with the penalties for missing them, in its official guidance on
GOV.UK.

Check Whether You Missed the 2021–22 Self Assessment Deadlines

If you are unsure whether your 2021–22 return or payment was completed on time, clarifying this now can help prevent further penalties or escalation. A short review can confirm where you stand and what steps may still be needed.

 

Need Help With Self Assessment Deadlines and Penalties?

Missing key Self Assessment deadlines can trigger automatic penalties and interest charges, even if you’ve paid the tax you owe. Specialist guidance can help you track the right submission and payment dates and manage any late filing or payment risk.

Speak to a Specialist About Your Self Assessment Deadlines

Trusted guidance from London-based accountants, focused on accuracy, clarity, and 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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