Political parties don't have to reveal source of the funds received below 20000 Rs. They take advantage of this loop hole. BJP claims that it has raised all the fund via voluntary contribution by people of India while Congress claims it to be acquired by sale of coupons.
Considering BJP and Congress are telling the truth and seeing the Times of Indian report of 2012, it would need 40 lakh voluntary contributions for BJP and 75 lakh coupon sales to Congress, each contribution/coupon cost to be 20000 Rs. I haven't heard of any such massive number of generous donations to BJP and Congress
There are three primary sources of income for these political parties.
...Read more