Most people know that the tax year is from 6 April to 5 April the following year, but there are other dates you must be aware of especially if you are required to fill out a self-assessment tax return. If in the last tax year you were self-employed, a company director, lived abroad and had a UK income.

And if your income was over £100,000 or you meet any of the other self-assessment tax return criteria, your online tax return should be submitted by 31^st January 2017. The tax you owe should also be paid by this deadline.

However, it’s useful to remember that there’s an additional payment deadline of 31 July if you make advance payments towards your bill. The deadline to register for self-assessment was 5 October 2016 and paper tax returns were due 31 October 2016.

If you submit your tax return late there are penalties, so it’s always best to leave a good amount of time before the deadline to get your return sent. If you can aim to submit your tax return before Christmas, you’ll save yourself a lot of stress and can enjoy the festive season fully.

If you miss the deadline to submit your tax return you will be charged £100. If your tax return is more than 3 months late, you will be charged £10 a day for up to 90 days, totalling £900 plus the initial £100 penalty. If your return is over 6 months late, you will be charged a fine of either £300 or 5% of the tax due, whichever is the higher, on top of the penalties above. At 12 months late another £300 fine or 5% of the tax due, whichever is higher, will be added to your bill on top of previous penalties. In serious cases, you may even have to pay 100% of the tax due on top of any tax you owe therefore doubling your payment.

If you miss the deadline for paying your tax the penalties are slightly different, and you will be charged interest from the date the payment was due. There are also penalties for mistakes on your tax return form if HMRC thinks you have been careless or purposely tried to mislead them. If you have deliberately underestimated your tax and attempted to conceal the fact, the penalty will be between 30% and 100% of the tax owed.

Never underestimate the importance of submitting your tax return and paying tax on time. You could end up paying serious money for your mistake. If you have any questions or think you may need assistance filling out your self-assessment tax return, call on 01623 490 120 or send us an email at This email address is being protected from spambots. You need JavaScript enabled to view it..