Five national parties have registered a growth in their income by 39 percent to Rs.1,275 crore in 2015 from the previous year, said a report by Association for Democratic Reforms (ADR). Unknown sources contributed to 54 percent or Rs. 685 crore of the funds collected in the year.

The ruling Bharatiya Janata Party (BJP) had the sharpest increase in its income by 44 percent to Rs. 970 crore from Rs. 673 crore in 2014. The party declared in its submissions that Rs. 940 crore came through donations, while the rest (Rs. 30 crore) from other sources.

Following the BJP, the Bahujan Samaj Party (BSP) and the Communist Party of India (Marxist) received Rs. 92 crore and Rs. 59 crore in donations to their annual income of Rs. 111.95 crore and Rs.123.92 crore, respectively. The Nationalist Congress Party (NCP) and the Communist Party of India (CPI) received donations of Rs. 38.82 crore and Rs. 72 lakhs to their annual incomes of Rs. 67.6 crore and Rs. 1.84 crore, respectively.

Talking about the link between donations and unknown sources, Lakshmi Sriram, programme manager at ADR, told International Business Times, India, that the definition on the modes of donations differ across parties filings to the Election Commission. Donations range from grants to party funds to sale of coupons to party newspaper sales.

However, "whatever the mode or form of payment, contribution exceeding Rs. 20,000 can be called as the only known source as the law mandates disclosure of name and address of the donor of such amount," said Sriram to IBTimes India. "The rest are all unknown sources," she added.

The report said that the BJP, which led the pack with 90 percent of its income from donations (Rs. 940 crore), was also the largest beneficiary from unknown sources, which amounted to nearly fifty percent, i.e., Rs. 437 crores.

In the most transparent of transactions, the NCP declared all its donation to be above Rs. 20,000 and therefore publicly accessible. However, the BSP said none of its donations was more than the stipulated amount, resulting in non-disclosure of names. The CPM, which earned 48 percent (Rs. 59 crore) of income from donations, had 90 percent of it from unknown sources.

The Indian National Congress (INC), which had Rs. 589 crore in funds as income in 2014, did not disclose its income tax returns for 2015 with the Election Commission of India (ECI) despite 141 days of lapse of the November 30, 2015, deadline.

Incidentally, the CPI was the only national party that witnessed a fall in its annual income by 24.28 percent (Rs. 59 lakhs) to Rs. 1.84 crore during the assessment year.