SOME taxpayers may unwittingly be stumbling headlong into a self-assessment pitfall because their last pay rise has taken them over the threshold without them realising.

Self-assessment taxpayers have less than a week to hit the September 30 deadline - and some may not even be aware that they now fall within the system.

If your employer gave you a pay rise in the last tax year (April 6 2003 to April 5 2004) which took your taxable earnings over £30,500 per year, you will have to file a self-assessment tax return.

But those who went over the £30,500 threshold last year are not the only ones who may now be liable to complete a tax return.

"If you embarked on self-employment, invested money (which is earning you interest), or have some new source of un-taxed income (perhaps because you let a property) then you too will need to fill in a tax return," said Andrew Hunt, associate tax director at the Salisbury office of chartered accountants and financial advisers Smith & Williamson.

If you can submit the return on or before Thursday, the Inland Revenue will calculate your tax and tell you what to pay by January 31 2005.

The Revenue should also collect underpaid tax of up to £2,000 through your code number if you are employed or have a pension with tax deducted under PAYE.

If you have not received a tax return but think you may need to pay tax, you must tell the Inland Revenue by October 5 2005.

A tax return will be sent to you and if you submit this within 30 days of the date of issue, the Revenue will still calculate your tax bill.

There are strict rules about keeping tax records.

If you are not in business, you must keep the records used to complete your tax return for 22 months from the end of the tax year.

If you are in business, you must keep your records for five years from the January 31 following the tax year: "All documentation should preferably be kept for six years," said Mr Hunt.

First published: Sept 27