Rate rationalisation was a plan envisaged by former Finance Minister Arun Jaitley. After the launch of GST, in 2017, the then Finance Minister Arun Jaitley had hinted at the scope of moving to a 3-slab structure. Jaitley in August 2017 had indicated that there could be scope for rationalisation of rates under the Goods and Services Tax (GST) as its implementation progressed.
Source: CNBC