Billed as a landmark move to curb tax evasion and corruption, the government's less than two week-old decision to recall 500 and 1000 rupee notes faces a graver challenge than the political bickering it has spawned. An NDTV investigation has found that for cuts ranging from 30 to 50 per cent of the total sum, middlemen are touting services in Delhi to launder 'black' or unaccounted money for others by using different bank accounts.