When is the Self Assessment deadline for tax year 2017-18?

The deadline for filing your online Self Assessment tax return for the tax year ending 5 April 2018 is midnight on 31 January 2019. There are other important deadlines throughout the year for self-employed earners too, so we’ve put together a guide for you to find out more.

January 2018 deadline for 2017 Self Assessment tax returns

If you brought home untaxed income between 6 April 2016 and 5 April 2017 - for example if you were self-employed or earning money from a rental property - the deadline for filing your online tax return for this period was 31 January 2018.

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If you’ve missed this deadline, you’ve probably already received a fine. But the fines keep piling up the longer you delay, so it’s important to file your tax return and pay any tax owed as soon as possible.

If you need a hand, check out our top tax return tips.

Self-employed income earned between April 2017 and April 2018

The last tax year ended on 5 April 2018. For untaxed income earned during the 2017-18 tax year, the online deadline for filing your Self Assessment tax return and paying your bill is midnight 31 January 2019.

Self Assessment deadlines in 2018

Before the next online tax return deadline comes around, there are several other 2018 Self Assessment dates to bear in mind. It’s unlikely that all of them will be relevant to you, but understand which ones apply so that you don’t miss any important deadlines.

  • 31 July 2018 is the deadline for making your second ‘payment on account’ instalment to HMRC. This will only apply to you if you were self-employed during the tax year 2016-17 and you owed tax of over £1,000 when you submitted your tax return for this period. Take a look at our payment on account guide if you’re not sure.
  • 5 October 2018 is the deadline for telling HMRC that you’re self-employed so that they’re aware you need to complete a tax return next year. If you’re already registered as self-employed, there’s no need to do this again. Check out our guide to registering with HMRC for more information.
  • 31 October 2018 is the Self Assessment deadline for the tax year 2017-18 if you want to file a paper return rather than filing online. However, most businesses find it easier to file their tax return online - and under the government’s Making Tax Digital plans, filing paper returns may not be an option from April 2020.
  • 30 December 2018 is the deadline for filing your online tax return if you want the tax owed to be collected through PAYE via your tax code. This is only an option if you have some income that’s already taxed through PAYE (i.e. you’re employed as well as self-employed), and if your Self Assessment tax bill for 2017-18 is below £3,000. See our article on tax codes for more information.

Self-employed income earned between April 2018 and April 2019

If you continue earning untaxed income from 6 April 2018, this will fall into the tax year 2018-19, which ends on 5 April 2019.

The deadline for filing 2018-19 Self Assessment tax returns will be midnight on 31 January 2020, although keep an eye on Making Tax Digital announcements in case there are any updates.

Although 2020 may sound like a long way off, it’s a good idea to start thinking about your tax return as soon as you start earning the money. For example, consider opening a business bank account to keep business and personal finances separate, keep all your receipts for tax deductible expenses, and use an app or a spreadsheet to keep track of your income. This will make everything much easier when it comes to filing your tax return.

Still feeling confused about Self Assessment dates and deadlines? Ask any questions in the comments.

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