GSt force to black money

Your Purchases are Known to Govt. thru your suppliers GSTR 1, on Any day Govt. may ask you to show Sale or Stock to verify the figures.

Only in Case of Un-Registered Dealers there is no provision to Identify your Purchases for Govt. but In Comming Months GSTR 1 will include PAN/Aadhar No of Un-Registerd Dealer to Identify Purchases.

Till Your Purchases you have paid GST , What Govt. will Loose is GST on your Margin. not Entire 18%. 

So Govt. Least bother for Billed supply or Non-Billed Supply....