After introduction of GST the value of inventory we have is excluding GST as the GST component (IGST, CGST, SGST, UTGST) is all separately lying as Input GST in our books of account and these are adjusted against Output GST. Even GST excludes the GST from the turnover in calculating aggregate turnover.
As GSTR 3B for March is filed between 1st and 20th April you will have Input GST as your asset and Output GST as your liability as your return is not yet filed. Even if you deposit money in Cash Ledger it will reflect as asset in Cash Ledger.
This aspect of GST is one of the grey areas that ought to be ironed out in the Income Tax Act for Section 44AD. The legal fiction is the higher the rate of tax, the higher your presumptive income because GST Rate varies from Nil to 28%. There is also a situation of Composition dealers who do not charge customers the GST. For the same product there will be varying income under presumptive scheme. Someone with a small turnover of 10 lakhs maybe forced into GST just because of interstate supply. He will have a disadvantage against a URD.
What will happen is a person with 10 lakhs turnover in North East state will have to show a higher income than a person with same turnover in other states only because of GST.