The total FDI in 2015-16 was $40 billion. 62% of FDI comes from two tax havens, Seyschelles and Mauritius, assuming 50% is black money, that’s $20 billion of black money pumped into India as FDI, in one year. Multiply that by 20 years, and you have about $400 billion dollars of black money invested as FDI.
The Swiss banks alone have reported that the money deposited in them by Indians is $1456 billion.
So the total black money generated in the last 20 years or so is about $1856 billion, without taking into account Austrian banks and Latvian banks.
That amounts to Rs. 129 trillion.
The total value of Rs. 500 and Rs. 1000 notes in circulation is Rs. 14 trillion ($200 billion). (source, Business Standard). Assuming that half of that is black/counterfeited money, that would mean Rs. 7 trillion ($100 billion) as black money.
Assuming all the black money would be checked, there will be no smart schemes to dispose off 500 rupee notes, all background verifications will be done for the depositors, that still means that just 5% of black money has been checked.
Now if you take into consideration all the scams already people have figured out to legitimize Rs. 500 and Rs. 1000 notes, that figure would drop even lower.
Note that I haven’t taken the value of all the property bought with black money, because I don’t have that data. Factor that in, and the number would probably drop to something like 1% or maybe lower.
So, is 5% or lower worth all the trouble?
I know there are many gross assumptions in the above. This is just a back of the envelope calculation, but it would be possible for someone to get the year-wise FDI investment and source, aggregate them, and come up with a more accurate figure.