Self-assessment Self-assessment tax returns

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A self-assessment tax return covers your income from all sources during the year.

Who has to make 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 ten 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.

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 2012-13, £10,900 for 2013-14)
  • 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.

Go further: Tax for the self-employed- deductible expenses and other points to consider  

Making 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.

The deadline for filling in the paper tax return is 31 October. After this you can still file your tax return online. The deadline for this is 31 January.

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. 

Go further: Self-assessment online- a step-by-step guide to making an online return

Self-assessment tax return fines

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

The longer you delay, the more you'll have to pay:

  • Three months late: a fine of £10 for each following day up to a 90 day maximum of £900. This is in addition to the fixed penalty above, so the overall fine could be £1,000
  • Six months late: a fine of either £300 or 5% of the tax due, whichever is the higher. This will apply on top of the penalties above
  • 12 months late:  another £300 fine or 5% of the tax due, whichever is the higher, will be added to your bill on top of the penalties above.

Checking your 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.

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