TAX chiefs are warning businesses in York and North Yorkshire they risk £100 fines by flouting today's self-assessment tax return deadline.

Miss it and firms will incur a late penalty charge of £100, as well as a £60-a-day fine.

If the return remains overdue in July, a further penalty of £100 will be added to the daily charges.

Furthermore, a penalty of up to £3,000 may be charged for each year in which inadequate records are kept.

Earlier this week, the Public and Commercial Services Union announced it will stage industrial action today, which could affect HM Revenue and Customs (HMRC) office opening times.

The 24-hour strike by 280,000 of the union's members is in protest against plans to slash 100,000 jobs across the country by next year.

However, HMRC has given assurances on its website that small businesses which find it impossible to file by today due to the industrial action should file as soon as possible tomorrow.

HMRC has said it will do everything it can to maintain normal services to the public and businesses while the strike continues.

Adrian Widdowson, a tax specialist with Garbutt and Elliott in York, said he did not think there had been a particular problem in York this year.

He said: "For small businesses working on your return can be a problem and the best thing is to take your return down to the local tax office or file it online as soon as possible.

"The industrial action should not cause too many problems this year, but HMRC is allowing some leeway in light of it."

It is estimated people across the country will put an extra £500 million into the taxman's coffers because of fines imposed for late returns, errors and charges on unpaid tax - an increase of £60 million on 2005/2006.

This year HMRC hopes the increased use of the internet to file returns will keep penalties and fines to a minimum.

Around two million returns were filed online in 2005/06, and this year the figure is expected to soar.

If you are registered for self- assessment online, you can file your return easily and securely up until midnight tonight at www.hmrc.gov.uk The fine for failing to send in a completed return for the 2005/6 tax year by today is £100, although it cannot be more than the unpaid tax.

Returns need to be completed only by those people who have been sent them, but if individuals know they owe tax, they are legally obliged to request one.