The registration in GST is PAN based and State specific. Supplier has to register in each suchState or Union territory from where he effects supply if he fulfills any of the following conditions
Having an annual aggregate turnover from all-India operations which is above the threshold limit of Rs. 20 Lakhs (Rs. 10 Lakhs for North-Eastern States).
Currently registered under any of the earlier indirect tax regimes
(VAT, Excise Laws,Service Tax Laws) irrespective of the threshold limit.
Having branches in multiple states or multiple business verticals in on state.
Making any supply to other states.
Required to pay tax under Reverse Charge
(In case your supplier is not registered under GST).
Required to deduct tax at source or an Input Service Distributor.
Supplying goods or services through E-commerce Operator.
Agents of a supplier.
E-commerce Operator / Aggregation who supplies goods or services under his brand name (e.g.Flip kart, Amazon, Ola).
Supplying online information and database access or retrieval services from a place outside India to a person in India, other than a registered taxable person.