Advice for last minute tax return filing

We've discussed previously the circumstances when someone might need to file a tax return. So now we're going to provide advice for last minute tax return filing close to HMRC's 31st January deadline.

Advice for last minute tax return filings

Are you registered with HMRC?

Perhaps one of the most fundamental pieces of advice for last minute tax return filing once you've determined it's necessary, is ensuring you're registered with HMRC. You'll need to have submitted an application to HMRC for a 10 digit unique taxpayer reference number - or UTR for short. 

This can be submitted via HMRC's online portal. If you haven't done so already, this should be done immediately to ensure you stand a chance of beating the deadline. It can take up to 10 working days from registration for the UTR to arrive. However, given the current operational issues with HMRC this will most likely take longer. Essentially without a valid UTR you'll be unable to submit your Self Assessment tax return online.

Preparing to file your tax return

Another key piece of advice for last minute tax return filing, is careful preparation. Start by compiling all the necessary documents and information. This can be daunting, especially if you're preparing it close to the deadline, though essential for accuracy as you want to avoid an HMRC enquiry where possible.

Typically what you'll need are as follows:

  • Personal Information: This includes your National Insurance number and UTR (see above).
  • P60 or P45 Forms: If you're employed or have recently left a job, these forms show your earnings and the tax you've paid.
  • Income Records: This encompasses all sources of income, for example self-employed earnings, income from employment, dividends, interest, foreign and rental income.
  • Records of Expenses and Benefits If you're self-employed, keep a detailed record of all business-related expenses. This includes any work-related expenses not reimbursed by your employer.
  • Charitable Donations: Records of any Gift Aid donations, as these can reduce your tax liability.
  • Capital Gains Information: If you sold assets like property or shares, you might need to report capital gains.

Avoiding pitfalls when completing your tax return

Filing a Self-Assessment tax return, especially close to the deadline, can be fraught with potential errors. 

We've covered these potential pitfalls in detail previously, though typically some common mistakes can include forgetting to include child benefit where you are a high earner or omitting your student loan details.

Being aware of how to avoid these errors can save you from exposure to potential penalties and an unnecessary HMRC enquiry. However ultimately it's better to file a tax return late and correct, rather than on time and wrong.

Other tips for successful last minute filing

Provisional and estimated figures

We would recommend you do not leave boxes in a tax return blank due to a lack of information. This is because HMRC will consider this to be an incomplete tax return, and penalties may be charged.

It is possible to use a provisional figure in a tax return temporarily, pending the later submission of the final or more accurate figure(s). However any provisional figure used should be reasonable and take account of all the information available.

However you should be mindful that HMRC might charge a penalty if there was no good reason for using a provisional figure, or it was not estimated reasonably.

Where your tax return contains a provisional figure this should be amended as soon as a correct figure becomes available or when the previously provisional figure should instead be taken as a final figure.

If an estimated figure in a tax return is intended to be accepted as the final figure because it is not possible to provide a more accurate figure you should Include a disclosure including the reason for using an estimate, in order to avoid penalties at a later date.

Making a disclosure

The main Self-Assessment tax return and additional pages (for example, Capital gains, Employment, Foreign) all have 'white space' information boxes to allow for more details to be provided to HMRC. 

These can be used for areas of doubt to ensure HMRC have full details to protect against discovery assessments. Due consideration should be given to what is disclosed here as it is considered to be part of your tax return Therefore penalties can result for inaccuracy in the same way as if boxes of the return have incorrect figures in them.

What happens if you file your tax return late?

Understanding the implications of late tax return filing can help you mitigate any adverse consequences.

Firstly, if you miss the 31st January deadline, you'll automatically incur a £100 penalty, regardless of whether you owe tax or not.

If your tax return is filed more than 3 months late, you'll start accruing daily penalties of £10 a day. Further penalties apply at 6 months and 12 months, which can be quite substantial.

Apart from penalties for late filing, interest is charged on any tax that is paid late. This starts accruing from the payment due date (31st January) until the date you pay.

Steps to take if you're late filing

If you are late, file as soon as possible. The sooner you file, the less you'll pay in penalties and interest.

Where  you can't file immediately, try to pay an estimated amount for your tax bill. This can help reduce interest charges.

However if you have a reasonable excuse for late filing, contact HMRC as soon as possible. They may waive the penalty in certain circumstances.


While it's best to avoid late filing, understanding the implications and knowing how to respond if you do miss the deadline can help mitigate the damage. Remember, clear communication with HMRC and prompt action are key in these situations.

If you're consistently struggling with meeting the deadline, consider seeking professional advice or using accounting software to better manage your tax affairs.

For more useful information, check out our Ebooks here.

And if you'd like to know how we can help you with all of this, or with anything else, feel free to give us a call on 01202 048696 or email us at [email protected].

Alternatively, please feel free to complete our Business Questionnaire here.

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