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In this article, we take a closer look at self-assessment filing deadlines and highlight some important issues. 

Already filed your tax return?

If you have already filed your tax return, don't forget you need to pay any tax due by 31st January. You are able to pay early or set yourself a reminder for nearer the time. If you pay your income tax late, HM Revenue and Customs (HMRC) will charge interest automatically once payment is 28 days overdue. 

If your self-assessment tax bill exceeds £1,000, you may have to make instalment payments for next year. These payments are called Payments on Account and individuals must pay them in January and July.  

Each payment on account is half of the previous year's tax bill. You can adjust these amounts if you expect your tax liability to reduce. 

If your tax return is still outstanding

If you are completing your own tax return, it's important to check your figures are correct and you've claimed your full entitlement to expenses, reliefs and allowances. 

HMRC's helplines will only deal with 'simple' queries such as questions surrounding PAYE coding notices or the Marriage Allowance. They do not offer tax advice. 

Get proactive and seek expert advice from our team at TaxAssist Accountants. We can take care of all your tax affairs for you, including: 

  • registering for self-assessment with HMRC 
  • completing your self assessment tax return 
  • calculating your tax liability 
  • advising you of deadlines and due dates 

An experienced accountant will also make sure your affairs are as tax efficient as possible. The key thing you need to do is make sure you get your accounting and tax records to your accountant in good time and give them as much information as possible. 

The deadline for paper tax returns is 31st October

There is the option to file your tax return on paper, the filing deadline is 31st October. However, submitting a tax return on paper after that date will result in an automatic late filing penalty of £100. Depending on how late you file your return, you may face further penalties. 

How to get ready to file your tax return online

If you are doing your own tax return, be aware that it takes time to register with HMRC, so it is vital that you factor in some processing time. 

HMRC will not send you a tax return to complete – it is your responsibility to register for self-assessment if necessary. 

Out of time? Use an accountant 

If you're concerned you won't have online access to HMRC before 31st January, contact an accountant or tax adviser. They should be able to file your tax return for you via their agent login with HMRC. 

You will need your Unique Taxpayer Reference (UTR) to submit your tax return. Your accountant can help you register for self-assessment and obtain a UTR if you don’t have one yet. 

Don’t leave it until 31st January

The more time you leave yourself to prepare your tax return, the better. This will reduce errors and mistakes, which could be costly. They could also mean that you have to amend your tax return. 

Try to avoid filing your tax return on these dates 

The busiest days for filing a tax return are 30th and 31st January. The busiest hour is 4pm to 5pm on 31st January. 

Although individuals have nine months to complete a tax return, almost half of tax returns are filed in January. 

We recommend you don’t leave your tax return until the final day of the deadline. HMRC’s website and call centres, as well as your accountant, will be under tremendous pressure. 

What happens if your file your tax return late?

A late tax return is subject to the following penalty regime: 

Automatic fixed penalty of £100 - even if no tax is due or tax has been paid on time 

  • After 3 months, additional daily penalties of £10 per day - up to a maximum of £900 
  • After 6 months, a further penalty of 5% of the tax due or £300 – whichever is greater 
  • After 12 months, another 5% of the tax due or £300 – whichever is greater. 

Each of these penalties is in addition to one another, so a tax return filed a year late could face penalties of at least £1,600. 

What to do if you cannot pay your tax bill? 

If you cannot pay your taxes, you should still submit your tax return to avoid the penalties for filing late. 

If you didn't pay on time, contact HMRC to discuss a possible payment plan or extension. Your accountant can also do this for you. 

There are late payment penalties of 5% of the tax unpaid at 30 days, six months and 12 months. Penalties are a waste of your hard-earned cash and you do not get tax relief for them. 

Need help with your tax affairs?

At TaxAssist Accountants we pride ourselves on helping you take care of all your tax affairs: from registration with HMRC and completion of your tax return, to calculating your tax liability and due dates.

So don't delay, contact us today to find out more about what we can do for you on 0800 0523 555 or by using our online enquiry form.

Date published 2 Jan 2019 | Last updated 12 Oct 2023

This article is intended to inform rather than advise and is based on legislation and practice at the time. Taxpayer’s circumstances do vary and if you feel that the information provided is beneficial it is important that you contact us before implementation. If you take, or do not take action as a result of reading this article, before receiving our written endorsement, we will accept no responsibility for any financial loss incurred.

Catherine Heinen, FCCA

Catherine is a Technical Content Writer at TaxAssist Accountants, and a qualified accountant. With experience working at two accountancy practices in the UK top 50 accountancy firms according to Accountancy Age, Catherine has significant experience in accounts, tax returns and advising clients. Catherine ensures businesses, business owners and individuals are kept up to date and informed by providing concise and informative technical material.

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