Intermediary services under GST require three parties, a facilitative role, and no principal-to-principal supply. Clarification under the GST framework explains the scope of intermediary services and aligns the definition with the pre-GST service tax position, with the added reference to supply of securities. The circular states that intermediary activity requires a minimum of three parties, namely two principals to the main supply and one person arranging or facilitating that supply, and that an activity between only two parties cannot be treated as intermediary service. It further emphasizes that the intermediary performs a supportive role and does not supply the main supply on its own account.