This discussion clarifies how suppliers should report Business-to-Business (B2B) supplies attracting Reverse Charge Mechanism (RCM) in their GSTR 1 returns. While the GSTR 1 guidance format suggests a specific table (4B) for RCM supplies, the portal interface requires a different approach. Suppliers need to disclose these transactions under the B2B section and tick the 'Reverse Charge' applicable box. It's crucial to select the correct tax rate relevant to the service (e.g., 5% for rent-a-cab, 18% for legal services). This ensures the supplier faces no direct liability and the recipient can view the RCM applicability in their GSTR 2A. The thread also addresses a specific scenario where the supplier (transporter) does not have a GST registration, confirming that RCM details for inward supplies are not to be shown in the supplier's GSTR 1.