Self Assessment Deadline 2017: Everything you should know

Filling out a tax return

What is self-assessment?

Self-assessment is the process of informing HMRC of your gains, income and other relevant expenses for a tax year. This is done by completing a tax return, forwarding it to HMRC and calculating your tax liability.

How to submit your tax return

There are two channels available to you to submit your tax return. You’re allowed to either send a hard copy tax return to HMRC or visit the HMRC website and fill the online tax return form.

Please note that the method you adopt in submitting your tax return will determine the deadline:

  • The deadline for filing hard copy tax returns is 31st October. This means that all hard copy tax returns relating to the period between April 2016 and April 2017 should be submitted on or before 31 October 2017.
  • Online tax returns need to be filed three months afterward – 31st January 2018. So you’re allowed until midnight, 31 January 2018 to submit your online tax return for tax returns relating to the period between April 2016 and April 2017.

Important dates you need to know for your 2016-17 tax return

In most cases, the date is said to be ‘during the tax year’ or ‘following the end of the tax year.’ Accordingly, a UK tax year runs from 6th April to the 5th of April the following year. This means that the tax year for 2017/2018, for example, would begin on 6th April 2017 and end on 5th April 2018. The 31st January during the tax year would be 31st January 2018, the 5th October following the end of the tax year would be 5th October 2018 and the 31st January following the end of the tax year would be 31st January 2019.

We advise that you put the following dates in your diary to avoid being fined for missing the tax return deadline.

  • 31st October 2017 – As mentioned earlier, this is the deadline for filing a hard copy tax return, irrespective of whether you decide to calculate the tax yourself or want HMRC to do the calculation for you. Nonetheless, if you get a notice asking you to file a return after 31st July 2017, you’re obliged to send back the completed form three months from the date you were issued the notice.
  • 30th December 2017 – If your tax return is done online and you had earnings less than £2,000 and taxed under PAYE, you can choose to have overdue tax collected by PAYE, provided you filed your online return before this date. This has the added advantage of flexibility in the sense that any tax owed would be paid over a 12 month period from April 2017, instead of in a single lump sum by 31 January 2018.
  • 31st January 2018 – With exception to situations where the HMRC issues the notice to make an online tax after 31st October 2017 and thus, gives you three months to make the issue, this is the final deadline for online tax returns. It is also the final deadline to fulfil tax obligations for hardcopy and online filers.


If you ought to send a tax return and you miss the deadline for submitting or paying your tax, you’ll be slapped with a penalty of £100 and the penalty increases the more the tax is left unpaid. Nonetheless, you can appeal against the penalty if you have a reasonable excuse.
Last year, thousands of people were penalised for late payment of taxes. Considering the fact that Christmas is just around the corner, you can avoid such a fate and take the time now to organise your finances.

If you want advice or help with your tax returns don’t hesitate to get in contact with us.

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