More than 77% of the total income of the Bharatiya Janata Party and the Congress in 2015-16 was from “unknown sources”, according to a report released on Wednesday. An analysis by the Association for Democratic Reforms found that Rs 646.82 crore of the Rs 832.42 crore income specified in their tax returns were from unknown sources.

Income from unknown sources refers to contributions below Rs 20,000 whose sources were not declared. This includes donations though the sale of coupons, miscellaneous income, voluntary contributions, relief funds and contribution from meetings or marches, according to the report.

Of the total income of Rs 570.86 crore declared in 2015-16, the BJP collected Rs 460.78 crore from unknown sources. Rs 186.04 crore of the Congress’ total declared income of Rs 261.56 crore was from unknown sources.

The BJP collected most of the funds – Rs 459.56 crore – from unidentified sources through voluntary contributions. The Congress’ main unknown source of income was the sale of coupons, by which the party collected Rs 167.96 crore in 2015-16.

The Association for Democratic Reforms is an NGO that works for electoral reforms. Its findings are based on an analysis of the income and expenditure data the two parties submitted to the Election Commission of India.