60 second guide to self-assessment tax returnsAll you need to know before the tax deadline

12 January 2013

Tax return

With less than three weeks to go to submit your self-assessment tax return for 2011-12, we explain all you need to know about the process.

Making a tax return is fairly straightforward but if you have any tax-related questions, the Which? Money Helpline has a team of qualified experts that can help answer them. Sign up to Which? for just £1 and speak to one of our experts.

Who needs to fill out a self-assessment tax return?

Most UK taxpayers have tax deducted at source (via PAYE) and don't need to fill in a tax return. However, around nine million people need to complete a self-assessment tax return (SA100 or SA200) and submit this to their tax office. 

Specifically, you'll need to fill in a tax return if:

  • You're an employee or pensioner with an annual income of £100,000 or more;
  • You have a pre-tax investment income of £10,000 or more;
  • You're a 'name' at the Lloyd's of London insurance market;
  • You're a minister of religion;
  • You're a trustee or representative of someone who has died;
  • You're self-employed, a business partner, or director of a limited company.

Self-employed people can find out more about how to keep their tax affairs in order by reading our tax for the self-employed advice guide.

You'll also usually be sent a tax return if:

  • You have untaxed income – from investment, land or property, or from overseas;
  • You make capital gains above the annual exempt amount (£10,600 for 2011/12 and 2012/13);
  • You were required to fill in a tax return last year;
  • You’re a pensioner over 65 who gets reduced age-related allowance, though you may be sent a special short version which requires fewer details.

How can I fill out a self-assessment tax return?

Anyone who receives a self-assessment tax return from HMRC is legally obliged to complete and submit it, either by post or online.

While the deadline for filling in the paper tax return passed on 31 October, you can still file your tax return online. However, you need to act sooner rather than later because the deadline is 31 January.

How hard is it to fill in a self-assessment tax return online?

Filling in a tax return online is relatively straightforward, even if you have not done it before. However, you need to register in good time and plan ahead to meet the 31 January deadline. Follow our 10-step plan to submitting a successful tax return online.

What happens if I do not file my self-assessment tax return before the deadline?

If you miss the 31 January deadline, you will automatically receive a £100 fine. This applies even if you have no tax to pay or have paid the tax you owe.

If, for whatever reason, you do miss deadline, the longer you delay, the more you'll have to pay so avoid incurring costly penalties and fines by sending your tax return to HMRC as soon as you can.

Can I get help filling in my self-assessment tax return?

You can work out how much tax you owe by using our tax calculator.

However, if you’re looking for someone to fill in your tax return for you or for some specific tax advice you can use a tax advisor. Visit our guide to choosing a financial adviser to find out what you need to look out for.

What should I do if I am not paying the right amount of tax?

Firstly, check your tax code is correct.

If you think you are paying too much tax, or not enough, visit our guide to tax appeals, disputes and complaints to find out what you should do.

More on this…