The deadline for filing an online tax return for the 2017-18 tax year is fast approaching. Self-employed workers are among the 11.5 million Brits who need to have sent a self assessment return by 31 January 2019 or risk being fined £100.

You’ll need to send a tax return via the HM Revenue and Customs website if you were self employed as a sole trader between 6 April 2017 and 5 April 2018. If you earn an income outside work, for example from rental property, you will also need to fill in a return. But don’t delay – if you have tax to pay, you’ll need to make your first payment (or pay the whole sum) before the end of the month. All returns filed after 31 January will be subject to a £100 late penalty.

But filing a tax return doesn’t have to be stressful – in fact, it’s much simpler than you may think. If your books are in relatively good shape and you have a record of how much you earned as a sole trader in the 2017-18 tax year, it shouldn’t be too much of headache.

Who needs to file? For the majority of UK taxpayers, tax is automatically deducted from wages, pensions or savings every month. But for businesses or individuals where tax isn’t deducted automatically, a self assessment tax return needs to be completed every year.

Get organised If you began your sole trader business in the 2017-18 tax year and haven’t filed a tax return before, you’ll first have to register for self-assessment. This can take a couple of days to activate, so don’t wait around to do this.