GST related query

Ajnas (Student) (844 Points)

26 January 2021  
1.ISD registeration is compulsory or optional?
2. For showing input in GSTR 6A of distribute r(head office) supplier which GSTN of receipent (Head office ) show in GSTR 1? normal GSTN of head office or ISD GSTN of head office?
3.if head office input is claimed in their GSTR1 not distributed to branches in GSTR 6 if any problem? It is required to reverse under "other Reversal" coloumn?