MPs have urged Revenue & Customs to get tough on businesses avoiding corporation tax and improve its investigations into compliance. In its latest report into corporation tax, the House of Commons Public Accounts Committee says the tax paid by large businesses is 'heavily skewed' towards a small number of businesses. Of the 700 largest businesses in the UK, 50 paid two-thirds of the tax raised in 2005-06 while 181 paid none. The committee, chaired by Edward Leigh, adds that businesses can legitimately reduce their corporation tax payments by claiming a range of reliefs and allowances. In some cases, the liability may reduce to zero, even though the businesses have made profits. Leigh said: 'The department aims to complete enquiries within 18 months, but 42% have been running for two years or more. 'Because of the delays, the companies affected cannot determine their final tax bill.' But the report has come under criticism. Kevin Hindley, managing director of adviser Alvarez & Marsal Taxand, said: 'There are often very legitimate reasons why companies obtain tax relief. The vast majority of the companies identified in the report as not paying tax are doing so because they are loss-making or don't have a significant UK presence.'