After around 20 years of implementation of GST (or in the distant future), what are the approximate changes that we will get to see in India?

GST is the biggest structural gamble we are taking with our entire economy in one shot. And to begin with, we are starting with a far more complex structure than what a real GST regime must be. Here are some changes I think will happen :

1. Informal to formal : If all goes well, our huge informal sector would have been formalised through sheer pressure of otherwise dying down. That will change India like nothing else will - if it happens without too much chaos.
2. Tax to GDP ratio : Our tax to GDP ratio should grow substantially over time. That will make huge resources available to the governments, which hopefully won’t fritter it away recklessly and inefficiently. Also, since all businesses worth any value would be under the tax net, hopefully public services delivery (administration, judiciary, police, local governance) will improve over time due to taxpayer pressure.
3. Corruption : Structural and systemic corruption would have been dealt a body blow, if the rationalisation of GST regime happens (multiple rates across multiple categories condensed to just one or two over 20 years), and if the GSTN portal actually works the way it’s being projected right now.
4. Simplicity : Simplicity in operations should make us a very attractive investment destination for many. But that’s a big ‘if’ as of now.
5. Speeding up : Tremendous speeding up of operations for companies should happen, leading to higher profitability.
6. Cyber attacks : Since the entire economy’s commercial data comes online on one portal, massive state-sponsored cyber-attacks (Pak+China) become a possibility. Coupled with online transactions post DeMo and Aadhar based authentication, we need a truly world-class and constantly evolving cyber-security regime. Are we upto it? I really don’t know.
7. Massive scale : Indian IT’s real mettle will be proven either way. GSTN will handle 300 crore invoices a month ( phew! ). Instead of a private ownership model, the GSTN is 49% government owned, and 51% non-govt FI owned.

The squeezing of a vast and vibrant informal economy (outside the tax net) where 9 out of 10 workers today work, is near certain. The destination-based nature of GST will put a lot of pressure on advanced, richer and manufacturing states testing the federal structure to the maximum. Inequalities in India have not reduced with time - they have grown. How GST ends up impacting it a going to be a great case study.

Source:https://www.quora.com/After-around-20-years-of-implementation-of-GST-or-in-the-distant-future-what-are-the-approximate-changes-that-we-will-get-to-see-in-India/answer/Sandeep-Manudhane