[tmbsundar]

6% is only the official estimate based on IT department raids. In reality, this will be more.

Moreover, if you stub out this 6%, you will arrest leakage of that black money getting converted into land, gold, assets etc.,

See an interesting discussion here, (though this conversation concludes both parties not conceding their point:-):)

https://www.reddit.com/r/india/comments/5cilgj/cash_has_only...

For a good argument in favor of the move, and for a theoretical perspective on this, even in a developed economy with less paper money %, please see Kenneth Rogoff's blog post and also his book - the "Curse of Cash" (I've not read his book though only his posts and tweets on this)

http://blog.press.princeton.edu/2016/11/17/kenneth-rogoff-in...