Don't rely too heavily on harried Hector

The official deadline for completing your tax return is just 12 days away if you want the Inland Revenue to calculate your bill for the year 1999-2000. But don't panic if there's no chance of getting your return in by 30 September.

The Revenue prefers tax returns to be submitted by this date because it allows sufficient time to deal with all the forms before the second payment is due on 31 January. But the Revenue will still do the calculation for you if the return is late - even by a matter of weeks.

Tax experts say that it is much more important to ensure that your return is correct than on time. Many people assume the Revenue will check the form for mistakes. But your tax liability is calculated by a computer that simply crunches the numbers fed in by a Revenue employee. If that employee is experienced, he or she may spot your errors. But there is no guarantee.

Likewise, you should check the resulting bill. The National Audit Office checked 3,400 calculations last year and found that 6 per cent were incorrect because Revenue staff had introduced errors. As about 9 million people are expected to file returns this year, 540,000 could find their tax bills are wrong through no fault of their own.

Eight per cent of 'corrections' made by Inland Revenue staff to obvious errors in returns were also wrong. Worryingly, the amendment of PAYE tax codes to collect balancing payments were dealt with incorrectly in 27 per cent of cases.

However, don't put off paying your tax bill until the sums have been checked. The Revenue will charge you 8.5 per cent interest on any amount that is found to be outstanding.

It would be easy to place all the blame for this scrappy service on the Inland Revenue. But the Government must share the criticism. At a time when the Revenue should be concentrating its efforts on making self-assessment work smoothly, the Government has burdened it with responsibility for running the complicated Working Families Tax Credit and for policing the national minimum wage. The Inland Revenue needs more staff, better training and an urgent review of its systems.

If you are having problems with your tax return and cannot afford professional advice, the charity TaxAid may be able to help. Call 020 7624 3768.