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Filing a Self Assessment tax return is a legal obligation for millions of individuals and businesses across the UK. Whether you’re self-employed, a landlord, or have additional income not taxed through PAYE, it’s important to file your return on time. Missing deadlines or failing to pay tax owed can result in financial penalties and interest charges from HMRC. This guide explains the key deadlines, outlines the penalties for late filing and late payment, and offers advice on how to appeal penalties and avoid them in the future.
Deadlines for Filing and Payment
Online vs Paper Return Deadlines
There are two ways to submit your Self Assessment tax return: online or by paper. Each has its own deadline.
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Paper tax returns must be submitted by 31 October following the end of the tax year.
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Online tax returns must be submitted by 31 January following the end of the tax year.
If you are filing for the 2023/24 tax year, the paper deadline is 31 October 2024, and the online deadline is 31 January 2025.
Key Dates to Remember
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5 April – End of the tax year
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31 October – Deadline for paper returns
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31 January – Deadline for online returns and payment of any tax owed
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1 February onwards – Late filing penalties begin
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28 February – Deadline to avoid surcharge on unpaid tax
Missing these key dates can trigger automatic penalties, so it’s vital to stay organised.
Late Filing Penalties
Filing your tax return after the deadline, even if no tax is due, will incur penalties. HMRC has a clear structure for fines, which increases the longer you delay.
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£100 Fixed Penalty – If your return is late by even one day, you’ll receive an automatic £100 fixed penalty. This applies even if you owe no tax or have already paid it in full.
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Daily Penalties After 3 Months – If your return is over three months late, you may be charged £10 for each additional day, up to a maximum of £900. This daily penalty is on top of the initial £100 fine.
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6-Month and 12-Month Further Penalties – If you still haven’t filed after 6 months, you’ll be charged the greater of £300 or 5% of the tax due. After 12 months, the same penalty applies again. In serious cases, HMRC can impose penalties of up to 100% of the tax owed.
Late Payment Penalties
Filing your return on time does not exempt you from penalties if you fail to pay your tax bill by 31 January.
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Initial Interest Charges – Interest begins to accrue from 1 February on any unpaid amount.
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Surcharge Penalties – A 5% surcharge is applied after 30 days, another 5% after 6 months, and an additional 5% after 12 months.
These charges can significantly increase your tax liability, so prompt payment is crucial.
Appealing a Penalty
What Counts as a Reasonable Excuse
Examples of valid excuses include:
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Serious illness or bereavement close to the deadline
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Unforeseen delays such as fire, flood, or postal strikes
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Technical faults with HMRC’s online services
For an excuse to be accepted, you must demonstrate that you took reasonable steps to meet your tax obligations as soon as possible after the problem was resolved.
How to Appeal Through HMRC
Appeals can be made:
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Online through your HMRC account
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By post using the penalty appeal form (SA370)
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By phone, in certain cases
You should provide evidence to support your claim, such as hospital letters or confirmation of system outages. HMRC aims to respond within 45 days, though it may take longer during busy periods.
Avoiding Future Penalties
Filing Reminders
Register for email or text reminders from HMRC to stay informed of approaching deadlines. Adding calendar alerts and setting early targets for submission can also reduce the risk of late filing.
Consider using accounting software or hiring a tax professional to help manage your returns.
Setting Up a Payment Plan
If you are unable to pay your bill in full, you may be eligible to arrange a Time to Pay plan. This allows you to spread the cost over a series of monthly payments.
You can set up a plan online if your debt is below £30,000 and you meet other conditions. Otherwise, contact HMRC directly to discuss your options.
Contact HMRC for Support
Helpline Details
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Telephone: 0300 200 3310
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Opening hours: Monday to Friday, 8am to 6pm
Online Services Available
You can also use your online personal tax account to:
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View deadlines and penalties
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File your tax return
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Set up a payment plan
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Check correspondence from HMRC
Frequently Asked Questions
Can I avoid penalties by contacting HMRC before the deadline?
Not unless you apply for a Time to Pay arrangement or have a recognised reasonable excuse. Simply informing HMRC won’t prevent a fine.
How quickly do penalties increase after the deadline?
The first £100 penalty is applied the day after the deadline. Further daily penalties begin after 3 months.
Is there a grace period after 31 January?
No. Penalties apply from 1 February for late returns or unpaid tax.
Can penalties be cancelled once paid?
No. If your appeal is successful, HMRC may refund the amount, but simply paying a penalty does not remove your right to appeal.
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