If this is the case why will GST not kick in the moment both houses of parliament clear the constitution amendment bill?

The constitution amendment bill only changes the overarching principle of indirect taxation in India in order to create a common market. Details of GST have yet to be worked out. It is only after details have been worked out can the final GST rates be fixed. Therefore, after the constitution is amended, the centre and states have to pass a separate legislation which fleshes out the details of GST. Eventually, this will be followed by subordinate legislation which details procedures.

In short, the constitution amendment is just the beginning of the legislative journey.

DISCLAIMER : Views expressed above are the author's own  Sanjiv Shankaran in Cash Flow . Courtesy Published by Economy, India | TOI