A savings scheme to help lceland staff save for Christmas could end up costing the supermarket at least £21m, after it was accused of breaching minimum wage rules.The scheme allows low-paid staff to have a sum deducted from their weekly paypacket and placed into a separate account, to be returned on demand, usually at Christmas. HM Revenue & Customs claims that, despite the voluntary nature of the scheme, the supermarket technically paid its staff below the minimum wage. It could now face a fine amounting to £3.5 million for each of the six years that the scheme ran.