The deadline for filing a paper tax return for the year ended 5 April 2009 was 31 October 2009.

But those who have yet to file their self-assessment will have to make a choice. They could still file a hard copy return, but this will be regarded as late and a penalty of £100 will be charged, although this can be reduced to nil provided all the tax due is paid by 31 January.

The only other alternative is to file online no later than 31 January, but in order to do so you must register in advance via the HM Revenue & Customs' website. A pin number will then be posted to you but it can take several days to arrive.

Those looking to make the deadline should follow these tips:

1. Register straight away for online filing. If you decide to file online, be sure to register as soon as possible as the registration process will take a few days.

2. Start in good time. It's important to find out now if anything is missing as you should (just about) have time to request duplicates or to hunt out vital information that never reached you in the first place.

3. Making estimates. If you do have to make estimates of your income, provide your best guess and explain your workings.

4. Additional employment. Remember to complete a supplementary page for each individual job or self-employment.

5. Reclaim tax on pension contributions. If you are a higher rate taxpayer and wish to reclaim the tax on pension contributions, remember to give the GROSS as opposed to the net figure for pension contributions. Again, this is an area which frequently confuses people and they lose out as a result

6. Get help. The tax form comes with help sheets. The Revenue has a help-line (0845 9000 444) and if you are internet-minded the Revenue website (www.hmrc.gov.uk) is a good starting point.

7. Don't underestimate your tax. If you miscalculate your tax and under-pay, you could be charged interest and a surcharge.

8. Consider whether your taxable income will reduce in 2009/10. If you anticipate a drop in your taxable income - for example, because bank interest rates have fallen - then you can agree a reduction in your payment on account with HMRC.

9. Pay the tax. Many people will need to make a tax payment which includes not only the balancing payment from last year's tax bill but also the first installment on account for 2009/10 tax year. Failure to pay the tax on time will lead to an interest charge.

10. Once you have filed your tax return, keep your records. If you are not in business, keep the records used to complete your tax return for 22 months from the end of the tax year. For the 2008/09 tax return, this means keeping records until at least 31 January 2011.

However, if you are in business, you must keep your records for five years from the 31 January following the tax year. So for the 2008/09 return, this means 31 January 2015.