There are different reasons why an individual might need to file a Self Assessment tax return. Not sure if you need to? Then this guide is here to help!

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Reasons to file a tax return:

• You were self-employed as a ‘sole trader’ and earned more than £1,000 (before taking off anything you can claim tax relief on)

• You were a partner in a business partnership

• You had a total taxable income of more than £150,000

• You had to pay Capital Gains Tax when you sold or ‘disposed of’ something that increased in value

• You had to pay the High Income Child Benefit Charge

• You had untaxed income from renting out a property

• You had untaxed income from tips and commission

• You had untaxed income from savings, investments and dividends

• You have received untaxed foreign income

 

There are other reasons you might want to file a return, even if one isn’t required:

• To claim some Income Tax reliefs

• To prove you’re self-employed, for example to claim Tax-Free Childcare or Maternity Allowance

• To pay voluntary National Insurance contributions

 

If HMRC issues you with a ‘notice to file a tax return’ then a return must be filed with HMRC, unless they are informed one is not required.

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If you are still unsure whether you need to file a tax return with HMRC, they have a handy tool to allow you to check.

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If you need to file a return for the first time

If you need to file a return, and haven’t done one before, you will first need to register for Self Assessment. HMRC has an online form to allow you to do this easily, and they will then post your Unique Taxpayer Reference (UTR) within around 4 weeks. If you know you need to file a return, you need to register for self assessment before 5th October.

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If you no longer need to file a return

If you don’t need to file a return for one year, or if you were self employed and no longer are, you need to inform HMRC of the fact.

If HMRC has issued you a notice to file a tax return, but one is not required, you will need to contact HMRC to let them know this.

 

The most effective way to do this is by phone, but this is not the quickest method. Unfortunately, calling HMRC can take a lot of time out of your day, but the best advice is to call before 9am or after 5pm (and not leaving it until January to call!) The number for Self Assessment General Enquiries line is 0300 200 3310 – you will need your UTR and your NI number to hand.

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HMRC also has an online digital assistant that should allow you to notify HMRC of a return not being required. You can find this here, and again would need your personal information including UTR and NI number to hand.

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If you have been issued a notice to file, HMRC are not notified that a return is not required, and a return is not filed, you will be automatically issued with a non-filing penalty of £100.

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If you were previously self employed and have stopped trading, you will need to notify HMRC. This guide provides the steps required to do this.

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Filing a Self Assessment

It is not a requirement that you have an accountant prepare or file a tax return with HMRC on your behalf, however it does ensure that the return is accurate, accounts for all available allowances (when self employed) and that there are no aspects of the return that might be missed.

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HMRC generally requires that a tax return is filed online, although they do still currently accept paper returns. The filing deadline for these is much earlier, to allow them to be reviewed before the January payment deadline. Future changes to Self Assessment however, is likely to remove the option for paper filing for most individuals, with the introduction to MTD for Income Tax. 

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HMRC has stated that MTD for Income Tax will be a legal requirement for sole traders or landlords with an annual qualifying income exceeding £50,000 from April 2026. The threshold lowers to qualifying incomes in excess of £30,000 from April 2027. These thresholds are based on total income from self-employment and property.

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Deadlines & Penalties:

• Filing deadline – 31st January

• Filing deadline for paper returns – 31st October

• Payment on account(s) – 31st January & 31st July

• Balancing payment – 31st January

• Late filing £100 – up to 3 months late, automatically issued from 1st February

• Interest on late payments at 7.5% accruing daily