The Upper Tribunal has granted permission for Grant Thornton UK LLP to go to the Court of Appeal on behalf of Total People.
The case relates to a National Insurance contribution (NIC) refund claim based on the difference between HM Revenue & Customs' (HMRC's) 40p per mile allowable rate and the 12p per mile paid by the employer plus an additional lump sum paid to the employees for using their private cars on business.
Total People was successful with its appeal to the First-tier Tribunal in August 2010 but, in HMRC's further appeal, the Upper Tribunal decided in favour of HMRC in August 2011 with a further amended decision issued in November 2011.
Grant Summers, Tax Partner at Grant Thornton UK LLP said: "We are pleased that the Upper Tribunal has acknowledged that this issue has wider implications.
"We are led to believe that the potential impact of this decision could be around £200 million.
"It is important that there is clarity about the conditions which must be met for payments of this kind to be exempt from NIC."