The 34-year-old Dane now has just to pass a medical and agree personal terms before finalising an initial £135,000 move to the German Bundesliga outfit.
"Thomas is expected to fly out to Germany tomorrow to try and agree personal terms and will undergo a medical on Wednesday," City Chief Executive Neil Doncaster told the clubs official website.
A clause has been added to the deal which means The Canaries will receive a further £34,000 once Helveg has completed ten games for his new side.