Taxpayers are “going to the wire” in filing their returns, resulting in a deluge of last minute self-assessment forms more open to processing errors by officials, according to MPs.

Edward Leigh, chairman of the Commons public accounts committee, has suggested that different types of taxpayer should be given different deadlines for their returns, in order to stagger the process more evenly throughout the year.

His committee has published a report showing that the Revenue and Customs agency made mistakes in processing almost 500,000 returns in 2004/2005.

People were undercharged for tax by £65m, while others overpaid to the tune of £30m. And 30,000 taxpayers were given incorrect penalty notices despite filing their returns on time.