A few companies are still ignoring the minimum wage law, research has shown. HM Revenue and Customs has the powers to issue a notice of underpayment if an employer is found to be flouting the legal threshold, which sits at £6.08 an hour for over-21s. Cases include that of a 21-year-old man who started as an apprentice mechanic four years ago and who still receives £4 an hour despite now being fully qualified.