Margin scheme for second hand goods

HARIPRASATH (Student) (43 Points)

17 July 2019  
My friend is selling 2nd hand mobiles. His turnover has crossed 20lacs for FY 2018-19. But he hasn't applied for GST registration. Now he is ready to get gst registration.

In margin scheme purchases from unregistered supplier by a registered person is taxable only on margin amount over the purchase amount.

Now that he is going to take registration can he avail margin scheme by paying RCM for all the purchases he made last year along with interest?