The National Audit Office (NAO) has begun an inquiry into self assessment tax returns, which will investigate the reasons behind instances of late and inaccurate filing.

According to the NAO, as many as 10 per cent of tax returns are filed beyond the due date, while 30 per cent contain inaccurate information.

The absolute deadline for filing your 2003/04 tax return is 31 January 2005. If you file your return late, it could trigger a penalty of £100.

Even though this date is a few months away, it would be prudent to act now and ensure that you have all the information you will need to fill in your return in good time, if you have not already done so. Your employer should have provided you with forms P60 and P11D, which detail the earnings and the expenses and benefits associated with your job. If you are self-employed, you will need your business income and expenditure records.

If you received dividends, you'll need the tax vouchers that were sent with the dividend payments. For all interest-paying accounts, you can request a tax certificate from your bank or building society.

Checklist.a guide to what you need

§       P60 from your employer

§      Copy of the P11D your employer sends to the Inland Revenue 

§      Annual statement of interest earned

§      For passbook-based accounts, have the interest credited in the last tax year entered

§      If you received income from the estate of someone who died or from a trust, you need form R185 from the estate administrators or trustees

§      Details of your profits if you are self-employed

§      Details of pension contributions made

§       Details of your Gift Aid donations

§      Details of any expenses you are able to claim