Investigation approval: Prior hierarchical authorisation and coordination required for cross jurisdictional and sensitive tax probes. CGST field formations must follow a structured regime where the (Pr.) Commissioner is responsible for approving and conducting investigations within their jurisdiction, coordinating with other formations or a central investigative channel when issues extend across jurisdictions or involve multiple registrations, and referring policy-sensitive interpretative issues to the relevant policy wing. Communications with listed or public entities should commence with official letters requesting specified records within a reasonable timeframe rather than summons; summons and letters must disclose the specific nature of the inquiry, avoid vague language, and not call for information already available on the GST portal. Prior reasoned approval for summons, e-file documentation, prompt conclusion of investigations, and an internal grievance officer are mandated.