Revenue sounds the last post for late returns

Self-assessment tax returns for the financial year 6 April 2002 to 5 April 2003 must be in the hands of the Inland Revenue by the last day of this month - and the taxman is coming down hard on those who fail to file on time. On top of the automatic £100 fine for missing the 31 January deadline, with further penalties the longer you take to return your form, the Revenue is now imposing an additional fine of £60 per day for persistent late offenders.

Of course, many people do not have to file tax forms because everything they owe has already been deducted from their pay packet. But others, including the self-employed and those with capital gains or income that hasn't been taxed at source, have a rendezvous with the Revenue. If you're one of these people, and have not yet opened the envelope containing your tax return, here is what you must do.

If you submitted your tax return on paper last year, you should have received a similar form for 2002-03. If you filed electronically, you are expected to file the same way again, and would not normally receive a paper version. If you can't find your tax return or have not been sent one, contact your local tax office immediately.

Alternatively, log on to www.inlandrevenue.gov.uk and investigate the electronic filing option. Remember it can take time to receive the paperwork and get organised to file electronically, so don't leave things to the last minute.

When completing the form, it helps to be systematic. Filling it in may not be a life-enhancing experience but at least tax returns are more logical than in the past and can be navigated - with patience.

Step one is to collate all the relevant papers affecting your tax position. The type of information you need depends on your sources of income and the allowable expenses you have incurred. For example, if you are an employee, you must give details of your pay and any benefits in kind you received during the year. This information should have been provided by your employer on forms P60 and P11D respectively. If you are self-employed, you need income and expenditure figures for the relevant accounting period.

Those with savings income will have to supply details of bank and building society interest payments and a breakdown of any dividends received during the year. If you have rental, capital gains or other sources of income, you must provide this information. You should have been sent the appropriate supplementary sheets to go with your tax return, but if the source of income is new, you may have to request them from the taxman.

Inevitably you won't have everything you require immediately to hand, so allow yourself enough time to make calls or dig out the necessary bits of paper. At worst you can include a "best estimate" but you must state that this is the case and supply the correct figure as soon as possible.

As well as completing your return, you will need to calculate - and pay - any tax due. This will include any balancing payment for the year 2002-03 and, if relevant, a first payment on account for the current tax year (2003-04).

For those with more complicated tax affairs, there is still time to seek help from a qualified tax adviser. The Revenue also has a self-assessment helpline, open evenings and weekends. Local tax offices provide a more personal, face-to-face service but are usually open only during office hours.

Your completed form can be sent by post, handed in to your local tax office (in which case, get a date stamp on a copy letter as proof of delivery) or put in a Revenue mailbox. Be careful if you are running late: some tax offices do not keep mailboxes open outside office hours, and 31 January falls on a Saturday this year.

The Inland Revenue helpline is on 0845 900 0444

Francesca Lagerberg is national tax director at Smith & Williamson, the independent professional and financial services group. Contact 020 7637 5377 or www.smith.williamson.co.uk