Do I need to fill in a tax return?

Most of us don't need to fill in a tax return as we pay our tax through our salary, but if your tax affairs are not that straightforward - or you have income from various sources - you may need to complete one. There are various categories that people fit into, but the major ones are as follows:

• You are self-employed or a director of a company
• You are a landlord or land owner who gets income from UK land and property (but if you're an employee and your income is less than £2,500, you might not have to fill one in)
• You receive an annual income from a settlement or trust, or income from someone who has died, and further tax is due on that income
• You have made profit from the sale of certain assets, called 'capital gains', and it has exceeded the amount worthy of tax exemption

You also may be affected if your tax affairs are complicated, which means that you:

• Earn £100,000 or more per year
• Receive 10,000 or more (before tax) from your savings and investments per year
• Claim against tax for professional subscriptions or expenses worth £2,500 or more
• Have untaxed income of £2,500 or more
• Owe tax at the end of the year that cannot be collected by the HMRC through a change to your PAYE code in the following year

When the Inland Revenue - now called HM Revenue & Customs (HMRC) - send you a tax return, you must always complete it and there are various deadlines which you are required to meet, depending on whether you want to work out the tax you owe yourself or, alternatively, you want HMRC to work it out for you. See below for more details.

How do I complete one?

If your affairs are not that complex, HMRC may have sent you the simpler tax return which is only four pages long, but generally the full tax return has ten core pages. If you've been sent the full tax return, you need to check that you have got the right pages, collate all the paperwork you'll need, complete the core and supplementary pages and send it back to your Tax Office by the deadline.

If the tax return is asking for exact figures and you don't know them, then always give an estimate instead. Never leave a box blank or say 'details to follow'. Always remember to sign and date the last page of the return once you have filled everything in.

If you have any questions about filling in your tax return, you can call HMRC's Online Services Helpdesk on 0845 60 55 999 - the line is open from 8.00 to 20.00, seven days a week.

What are the self-assessment deadlines and penalties?

Here's an outline of the annual deadlines:

• 31 October - the final deadline for paper tax returns for tax years ending 6 April 2008 and onwards. The previous deadlines of 30 September (for submitting your paper tax return) and 30 December (the final paper deadline for HMRC processing it) no longer exist.

• 30 December - the deadline for doing the process online, if you want HMRC to collect tax through your tax code (if possible) where you owe less than £2,000.

• 31 January - the final deadline for sending back an online tax return which you received before the previous October. If HMRC don't receive it until after this date, you will be fined £100.

  31 January is also the deadline for paying the balance of any tax you owe, if you were sent a tax return by the previous 31 October. HMRC will then charge you interest for every day after this date if you don't pay. By 31 January you will also have to make your first 'payment of account' for the current tax year. In other words, you will have to pay the balance of the tax owing for 2006-7 and then the first payment on account for 2007-8.

• 31 July - the second deadline for tax owing for the preceding tax year.

For more information and assistance on completing your tax return, visit HMRC's website at http://www.hmrc.gov.uk/sa.

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