Value of supply of goods or services or both between distinct or related persons, other than through an agent :
The value of the supply of goods or services or both between distinct persons as specified in section 25(4) and 25(5) or where the supplier and recipient are related, other than where the supply is made through an agent, shall,- (a) be the open market value of such supply (b) if open market value is not available, be the value of supply of goods or services of like kind and quality (c) if value is not determinable under clause (a) or (b), be the value as determined by application of rule 4 or rule 5, in that order.
Section 25(4) and 25(5) of CGST Act covers those cases where same person has taken separate registration in different States or even in the same State.