Plans for a single taxation system across India have been kicking around for more than a decade, but when the Goods and Services Tax (GST) bill comes before the upper house, it is expected to be passed.

A central plank of Prime Minister Narendra Modi's economic agenda, it proposes a centralised tax to cut through the red tape and corruption generated by the swathe of state taxes currently in force.

Many economists say it will also boost gross domestic product (GDP).