HM Revenue & Customs is dealing with 13,000 VAT overpayment claims from businesses - an 'unprecedented' amount which has resulted in the department setting aside £5bn for potential claims cases. An HMRC spokesperson said: 'I don't think we have had a similar case before. It is a rather unusual situation'. A ruling on a case last year in the House of Lords on Aston Martin dealer Michael Fleming, is said to be one reason the authority has set aside such an amount. Overpayment on VAT could be backdated for up to six years until 1996 when a three-year threshold was placed on company claims. But the ruling in the Fleming case meant that companies were given until March 2009 for any additional backdated claims. The Financial Times reported that HMRC has already paid £1.5bn on an unrelated case due to the impact of the Fleming case. The claims are said to have contributed to the £32bn drop in HMRC's net revenues compared to the previous year.