If you leave your tax returns until after midnight 31 January, you will instantly be hit with a £100 fine that can reach up to £1600 if you keep delaying.
The majority of people who are required to file a tax return will know the deadlines well in advance. These include those with more complex tax affairs and the self-employed.
HMRC usually sends out tax returns in April (the end of the tax year).
If you did receive a return for the tax year 2013-2014, you are too late to file it by post as the cut off date for that was 31 October. The later deadline of 31 January is still available if you go online with the added bonus of on-screen help and automatic calculations.
To submit your tax return online you need to be registered with the HMRC online services. To do this, you will need an activation code by post, which usually takes a couple of days to come through. If you need to register, do it as soon as possible here: online.hmrc.gov.uk/registration/individual.
While you are waiting, it’s a good idea to gather all of your relevant documents including bank and savings statements ready for filing.
Unsure if you need to fill in a self-assessment tax return? You can check if it applies to your business here: gov.uk/check-if-you-need-a-tax-return.
When you are registered for self-assessment, you typically pay tax twice a year. January 31 will be the date to pay the balancing payment for 2014-2015 and the first payment for 2015-2016. This will be separate from penalties for late filing for 2013-2014.
The HMRC online services helpdesk is available on 0300 200 3600 if you have any queries when filling out your self-assessment forms.