If you haven’t filed your self assessment tax return yet, you should do it as soon as possible.

The online deadline is 31 January and there are only a few days left. Many people delay it until the last minute and end up making costly errors in their rush to finish it on time.

Who needs to file a tax return?

You need to file a tax return if you earned any self-employed income or received any untaxed income above £1,000.

But self-employed people are not the only ones who need to complete a self assessment tax return. You also need to file one if you had any untaxed income from:

• renting out a property, including through Airbnb;

• commissions and tips;

• savings, investments and dividends; and/or

• income from abroad.

This is not a complete list. If you are not sure whether you need to file a tax return, please contact HMRC or get professional advice.

How to avoid five common mistakes

     Start early: It takes more time than you expect to collect all the documents you need. This includes your P60, which shows how much tax you paid. You also need your P11D or P9D forms, which have your benefits and expenses. And if you quit a job in the last tax year, you need your P45 from your former employer.

     Claim tax relief on your pension contributions: Keep track of how much you paid into your pension to get the right tax relief.

     Don't forget your charity gift aid payments: You also need to record all your gift aid payments - for example, did you donate to a friend's charity run? HMRC gives you some tax relief for your charitable donations, which you can include.

     Save a copy of your finished tax return: If you have a job or a pension, you need to keep all your documents for 22 months after the tax year ends. Self-employed people or landlords need to keep them for five years and 10 months.

     Use your personal savings allowance: This applies to the interest you earn on your savings. You could get up to £5,000 per year of interest tax-free.

It is very important to file your tax return on time. Otherwise, you will get a £100 penalty, which will go up if your return is more than three months late.

If you are making a payment from abroad, make sure you allow enough time for it to go through.

For more information on how to file your return, including how to pay and set up a payment plan, go to HMRC’s website.

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