What Happens If I Miss The Deadline To Submit My Tax Return Form?

However, life happens: illnesses, unexpected emergencies, and even simple oversight can cause you to miss the deadline.

When that happens, knowing the consequences and, more importantly, your options can make a big difference in how much you ultimately pay and how you smoothly manage your tax affairs moving forward.

This guide will explain what happens if you miss the tax return deadline, what penalties you face, how to minimise damage, and steps you can take to avoid future issues.

Understanding UK Tax Return Deadlines

The UK operates on a strict tax timetable:

Self Assessment (for Individuals, Sole Traders, Partnerships):

• Paper tax return: Due by 31 October following the end of the tax year.
• Online tax return: Due by 31 January following the end of the tax year.
• Tax payment: Also due by 31 January.

Corporation Tax (for Limited Companies):

• Corporation Tax Return (CT600): Due 12 months after the end of your accounting period.
• Corporation Tax payment: Due 9 months and 1 day after the end of your company’s accounting period.

Important: Missing any of these dates, even by one day, can lead to automatic penalties, interest charges, and increased risk of an HMRC investigation.

Immediate and Long-Term Consequences of Missing the Deadline

If you miss the self-assessment deadline:

• 1 day late: £100 automatic penalty (even if you owe no tax)
• 3 months late: £10 daily penalty (up to 90 days; maximum £900)
• 6 months late: £300 penalty or 5% of tax due (whichever is greater)
• 12 months late: Further £300 or 5% of tax due (whichever is greater)

Corporation Tax Late Filing Penalties:

Corporation Tax penalties are slightly different but equally strict. Missing the Corporation Tax filing deadline triggers:

• 1 day late: £100 penalty
• 3 months late: Additional £100
• 6 months late: HMRC estimates your Corporation Tax bill and adds a 10% surcharge
• 12 months late: Another 10% surcharge on unpaid tax

Note: If your company tax return is late 3 times in a row, the £100 penalties are increased to £500 each.

Interest on Unpaid Tax

In addition to penalties, HMRC charges daily interest on any unpaid taxes starting from the original due date.

• As of 6 April 2025, the late payment interest rate is around 8.50% annually.
• Interest charges are non-negotiable; you cannot appeal them unless the underlying tax charge itself is overturned.

Possible Surcharges

If you continue to delay payment after receiving penalty notices, HMRC can impose additional surcharges. For example, after 30 days of non-payment, a surcharge of 5% of the unpaid tax may be added, putting further pressure on your finances.

Risk of Investigation or Audit

Consistently missing tax deadlines or failing to communicate with HMRC can increase your chances of facing an investigation. HMRC may review your accounts more closely to check for carelessness, errors, or intentional evasion. Investigations can be stressful, expensive, and time-consuming, and even unintentional mistakes could lead to additional penalties.

Impact on Creditworthiness and Business Standing

If unpaid taxes lead to court judgments against you or your business, it can negatively affect your credit score. Public financial data showing outstanding HMRC debts can make it harder for you to secure loans, win contracts, or build partnerships, especially if you run a limited company.

If You’ve Missed the Deadline: What You Should Do

Submit Your Tax Return Immediately

Even if you cannot pay the tax you owe, you should submit your tax return as soon as possible. The penalties for late filing are separate from the penalties for late payment. Filing the return immediately helps limit how much your penalties can grow and shows HMRC that you are trying to fulfil your obligations.

Pay What You Can

It’s better to pay a portion of your tax bill than to pay nothing at all. Partial payments reduce the amount of unpaid tax that will accrue interest charges, and they demonstrate good faith to HMRC, which can work in your favour if you later need to negotiate payment terms.

Contact HMRC and Explain

If you have a reasonable excuse for missing the deadline, such as a serious illness, bereavement, or technical issues with HMRC’s online services, you should contact HMRC as soon as possible. In some cases, penalties can be reduced or cancelled if you can provide sufficient evidence to support your claim. However, not all excuses are accepted, simply forgetting, lacking funds, or not receiving a reminder from HMRC are generally not considered valid reasons.

Request a ‘Time to Pay’ Arrangement

If paying your entire tax bill at once isn’t possible, you can apply for a Time to Pay arrangement. This allows you to spread your tax payments over a longer period, sometimes up to a year. Applications are reviewed individually; approval depends on your financial history and willingness to cooperate.

Tip: Apply before HMRC initiates legal action.

Proactive Tips: How to Avoid Missing Deadlines Again

• Register for HMRC emails or text alerts to get deadline reminders.
• Start preparing your return early (at least 3 months before the deadline).
• Keep digital and physical copies of all important documents like invoices, receipts, and bank statements.
• Make advance payments if you anticipate a large tax bill (especially useful for sole traders).
• Factor taxes into your monthly cash flow, so you’re not scrambling for cash in January.
• Understand your tax obligations fully if you’ve started a new venture, changed employment status, or received grants or benefits.

Conclusion

Missing a tax return deadline can lead to significant financial penalties, interest, and even reputational damage, but it’s not the end of the world if you act quickly. By filing as soon as possible, communicating proactively with HMRC, and setting up systems to manage your taxes better in the future, you can regain control and protect your business or personal finances.

Need help filing your tax return or setting up better systems?

Taxd makes it easy to stay compliant, avoid penalties, and manage your tax responsibilities with confidence. Whether you’re a sole trader, landlord, or limited company owner, our easy-to-use platform helps you file accurately and on time.

Get started with Taxd today and never miss another deadline!

FAQs

1. I missed the tax return deadline by just one day. Will I still get a penalty?

Yes. HMRC applies the £100 penalty even if you're just one day late. There's no grace period.

2. What happens if I keep ignoring HMRC letters after missing the deadline?

Penalties and interest will keep accumulating. If ignored, HMRC can escalate matters by involving debt collectors, seizing assets, or initiating court proceedings.

3. How long does it take HMRC to process a penalty appeal?

Appeals can take between 2 weeks to 3 months, depending on the complexity. Providing clear evidence speeds up the process.

4. Can I still submit my tax return if I don't have all my documents?

Yes, but you must correct the return later if needed. It's better to submit a reasonable estimate than to miss the deadline entirely.

5. Is it better to file a "nil return" than to miss the deadline?

Absolutely. Even if you owe nothing, submit a "nil return" to avoid automatic penalties.