The implementation of the landmark goods and services tax (GST) regime, proposed from April 1, 2016, would increase India's gross domestic product (GDP) by one to two per cent, Finance Minister Arun Jaitley said on Thursday.
"This (GST) has the potential to push India's GDP by one to two per cent," Jaitley said at the Peterson Institute for International Economics in Washington, adding that the landmark constitutional amendment would immediately convert India into a one big uniform market, which will benefit all stakeholders.

Source - http://www.business-standard.com