New Delhi: It is projected that India's swelling working age population is expected to increase the income of poor states as well as boost the overall growth.

According to an IMF working paper, working population is generally defined as those between the age group of 15 to 64 years.

"It is the poorest Indian states that stand to gain the most from the forthcoming demographic transition, since they are the ones that have so far lagged behind in both transition and in income growth," the recently released paper by Shekhar Aiyar and Ashoka Mody said.

As per estimates, the world population is to grow by 2.4 billion people. About a quarter of the projected increase in the global population aged 15–64 years between 2010 and 2040 is supposed to be from India.

The trend of rising number of working age population, also termed as "demographic dividend", is mainly due to declining infant mortality rates as well as falling fertility rates.

"The working-age ratio in the country is set to rise from about 64 per cent currently to 69 per cent in 2040, reflecting the addition of just over 300 million working-age adults.

"This would make India—by an order of magnitude—the largest single positive contributor to the global workforce over the next three decades," the paper noted.

According to the paper, whose views need not necessarily represent that of IMF, the demographic dividend factor would bolster India's per capita income in the coming decades.

"The bulk of the remaining demographic transition will be concentrated in lagging states, thus raising the prospect of substantial income convergence among rich and poor states," the paper said.