New Delhi, April 30

Only about two per cent of Indians filed income tax returns in 2013, long-awaited official data showed on Friday, highlighting an exceptionally low tax base that constrains public spending in the world's second-most populous nation.

The government was nudged into releasing the figures after celebrated Economist Thomas Piketty in January criticised the difficulty of measuring India’s wealth distribution since New Delhi stopped publishing income tax data in 2000.

Some 28.8 million individuals filed income tax returns in fiscal year to March 2013, the most recent for which figures were given — around 2.3 per cent of India's 1.25 billion population.

In biggest group of taxpayers, two million Indians declared average annual earnings of INR 694,000 ($10,400). The returns are noticeably sparse at high end, with just six individuals declaring average income of $10.4 million in top-earning group.

India has at least 84 billionaires, as per Forbes magazine.

It suggests a searing shortfall in the amount of income tax paid by the very rich in India, a vastly unequal country where much of the wealth is concentrated in the hands of a few.

PM Narendra Modi's government has stepped up efforts to crack down on illicit income and assets known as ‘black money’, often stashed abroad in form of property or in undisclosed bank accounts.