Missed the Self Assessment filing deadline? Here’s what to do

The deadline for submitting a Self Assessment tax return online is midnight on 31 January each year. If you missed the Self Assessment filing deadline for the previous tax year, you should send your tax return as soon as possible. Depending on how quickly you do this, you may be able to minimise the late filing penalties applied by HMRC. 

In this article, we explain what you need to do if your tax return is overdue. We also discuss the penalties that apply when you miss the Self Assessment filing deadline and do not pay your tax bill on time. If you are unable to pay your bill in full, there are options available to you.

File your late Self Assessment tax return as soon as possible

Missing an important deadline is always unfortunate, but try not to panic. You can still file your Self Assessment tax return (SA100) online or by post, so just focus on getting this done as soon as you’re able. Online filing is much easier and quicker (and you’re less likely to make a mistake), so use this method if you can.

There is no need to contact HMRC before doing so. Simply file your tax return as you normally would. If this is your first time sending a Self Assessment tax return to HMRC, you may find the following guides helpful:

• How to register for Self Assessment
• Do I need an accountant to do my Self Assessment tax return?
• The top 10 Self Assessment tax return mistakes – and how to avoid them
• 12 Self Assessment expenses you didn’t know you could claim

You need to be registered for Self Assessment before you can file your first tax return. The registration deadline is 5 October (almost 4 months before the tax return is due). If you register after this date, a ‘failure to notify’ penalty may apply if you also deliver your tax return late.

If you normally send a paper tax return

If you normally send your Self Assessment tax return by post but end up missing the filing deadline of 31 October, you still have an extra 3 months to file it online before it is deemed late. Paper tax returns are only due earlier because it takes HMRC more time to process them than online returns.

As long as you send it online on or before 31 January, you won’t have to pay a late filing penalty. However, HMRC will apply the standard penalties if you file the late tax return on paper after 31 October.

When the filing deadline is different

If you would like HMRC to automatically collect your Self Assessment tax through your PAYE tax code, you must submit your online tax return on or before 30 December rather than 31 January.

If you are a non-resident company or a trustee of a registered pension scheme, you must send a paper tax return on or before 31 January (3 months after the standard Self Assessment filing deadline for paper returns). You cannot send an online return.

Self Assessment late filing penalties

Unfortunately, you will have to pay a late filing penalty of £100 if your Self Assessment tax return is up to three months late. Further charges will apply if it is even later.

HMRC will also charge penalties and interest if you fail to pay your tax bill on time. The payment deadline is midnight on 31 January – exactly the same as the online filing deadline.

You can use HMRC’s online calculator to estimate your penalties for missing the Self Assessment filing deadline or paying your tax late. However, it won’t take into account any of the following:

• Payments that you have made toward your tax bill
• Outstanding interest or penalties for earlier tax years
• Any credit you have from previous tax years

If you have a reasonable excuse for why your tax return (or payments) were late, you can appeal to HMRC against a Self Assessment penalty. A reasonable excuse is something that prevented you from meeting tax obligations that you took reasonable care to meet, such as:

You will need to provide the following details on the form:

• Name and address
• Unique Taxpayer Reference (UTR)
• The date on which HMRC issued the penalty
• The date on which you filed the tax return
• Penalty (or penalties) you want to appeal against
• Your reason for making an appeal

If your appeal is upheld and you don’t have any outstanding tax to pay, HMRC will refund the penalties you’ve paid, including interest.

If you cannot afford to pay your Self Assessment tax bill

You may be able to set up a ‘Time to Pay’ payment plan with HMRC if you cannot afford to pay your tax bill. This arrangement will enable you to spread the cost of your latest Self Assessment bill over a number of months, giving you more time to pay and get back on track.

You can set up a payment plan online if all the following apply:

• You owe £30,000 or less
• You don’t have any other payment plans or debts with HMRC
• You’ve filed your latest Self Assessment tax return
• It is less than 60 days since the payment deadline passed

You can choose how much you would like to pay immediately (if you can afford to do so) and how much you’d like to pay each month. To set up a payment plan, you will need:

• Your Unique Taxpayer Reference
• Your UK bank account details (to set up a monthly Direct Debit with HMRC)
• Details of any previous payments that you have missed
• Details of your income and spending (to work out how much you can reasonably afford to pay each month)

HMRC has a helpful YouTube video that shows you how to set up a Time to Pay payment plan online.

If you cannot set up a payment plan online

You will need to contact HMRC directly if you are unable to set up a payment plan online for any reason. They will ask you for the following information:

• Why you are unable to pay your tax bill
• How much you can afford to repay each month
• If you have any other taxes to pay
• How much money you earn
• Your monthly outgoings
• Whether or not you have any savings or investments

If you have savings or assets, HMRC would normally expect you to use these to pay as much of your tax bill as possible.

If you have taken independent debt advice (e.g. from Citizens Advice or StepChange), you may have a ‘Standard Financial Statement’. HMRC will accept this statement as evidence of your monthly earnings and personal expenses.

Once you have paid all of the tax that you owe, you should consider setting up a Budget Payment Plan with HMRC to make regular weekly or monthly payments toward your next Self Assessment tax bill.

Is late filing information shared publicly?

HMRC will not publicly disclose any information about your Self Assessment tax returns or bills. You do not have to worry about clients, lenders, credit reference agencies, or anyone else finding out, so it should have no impact on your personal or business reputation.

For this reason, any debts you owe to HMRC won’t negatively impact your financial health or reduce your chance of obtaining credit.

However, if these debts remain outstanding and you do not engage with HMRC or attempt to pay what you owe, the outcome may be very different. Under such circumstances, HMRC may:

• use a debt collection agency to settle your debt
• directly recover your tax debts from your wages or any monthly pension payments you receive
• take things that you own and sell them (unless you live in Scotland)
• take money directly from your bank account or building society savings (unless you live in Scotland)
• take you to court
• start bankruptcy proceedings

As long as you contact HMRC as soon as possible and try to come to an arrangement, you shouldn’t have to worry about any of these things. HMRC will only use its tax debt enforcement powers where a person or business deliberately avoids paying their tax bills.

Self Assessment dates for your diary

The Self Assessment filing deadline and payment dates are the same every year. They fall after the end of the tax year, so you always have several months to prepare your tax return and pay any tax that you owe.

The tax year runs from 6 April in one year until 5 April in the following year. We are currently in the 2024/25 tax year, which ends on 5 April 2025.

Add the following dates to your diary to avoid missing any deadlines in future tax years:

• File a Self Assessment tax return by post – by midnight on 31 October
• File a Self Assessment tax return online – by midnight on 31 January
• Pay your tax bill – by midnight on 31 January
• Make a first ‘payment on account‘ – by midnight on 31 January
• Make a second payment on account – by midnight on 31 July

If you need to file a tax return for the current 2024/25 tax year, you must send it on or before 31 October 2025 (paper return) or 31 January 2026 (online return). Any tax that you owe for the period covered in your tax return must be paid in full by 31 January 2026.

• How to reduce your Self Assessment payments on account 

You may also be required to make a first payment on account on or before 31 January 2026 if your last tax bill was more than £1,000. A second payment on account will then be due on or before 31 July 2026.

Lots of people get caught out by payments on account, so take care and make sure that you’re putting enough money aside each month to cover your tax bill. If you’d rather not set up a Budget Payment Plan with HMRC, consider putting the money in a high-interest savings account, ready to use when it’s time to pay your Self Assessment bill.

Thanks for reading

Keeping on top of your tax obligations can be challenging, especially if you have other demands on your time. Being faced with penalties for missing the Self Assessment filing deadline or paying your tax bill late just adds to the stress.

If you are within three months of the most recent online filing deadline, try to send your tax return as quickly as you can. By doing so, you will avoid further charges on top of the £100 automatic penalty. If you are also late paying your tax bill and you are struggling financially, set up a payment plan with HMRC.

Depending on your circumstances, it may be worthwhile using an accountant or tax advisor for future tax returns. This may help you to avoid missing the Self Assessment filing deadline in future years.

Please feel free to leave a comment below if you have any questions about this post. For more small business advice and tax guidance, explore the 1st Formations Blog.