It has been predicted that £479 million will be paid to HM Revenue & Customs (HMRC) this year as Britons fail to meet the the self-assessment tax return deadline.

According to independent financial advice website Unbiased.co.uk the penalty charges will be £16 million higher than last year's estimate.

The sum, which is made up of fines for late returns, surcharges and interest on unpaid tax, will amount to nearly £479 million, but £102 million of this will be fines for self-assessment forms that are returned after the January 31 deadline.

People who fail to return their self-assessment form by January 31 face an automatic £100 fine, followed by a further £100 fine levied if the form is still not returned by July, as well as the additional charge of interest on any outstanding tax.

However, a majority of the sum, a total of £315 million of fines, will be collected by the taxman for people who have mis-calculated how much they owe in tax.

It is also predicted that consumers will pay £62 million in surcharges on unpaid tax from previous years.

David Elms, chief executive of Unbiased.co.uk, said: "The penalties for those who return their self-assessment forms late or incorrectly remain unforgiving.

"Missing the HM Revenue & Customs' deadlines inevitably results in hefty fines, and in the current climate more than ever we would urge consumers to avoid this by ensuring that their forms arrive on time and in order."

A HMRC spokesman said that 900,000 taxpayers missed the deadline last year, a total of 10% of all the people who fill in the forms, but half of these did not face a charge as they did not owe any tax and any penalty imposed cannot exceed the amount of tax owed.

The spokesman has urged people who are struggling during the economic downturn to contact HMRC, as it may be possible to set up a suitable payment arrangement.

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