Suspension of registration for significant return discrepancies triggers portal notice and requires taxpayer reply before further cancellation action. Immediate suspension of registration follows where return comparisons reveal significant discrepancies indicating contravention and threat to revenue; affected taxpayers receive an electronic intimation and notice on the portal or e mail, must reply online in the prescribed form addressing anomalies and may cure defects such as filing overdue returns. The jurisdictional proper officer reviews responses or expiry of the reply period and may revoke suspension or cancel registration, updating the GSTIN status accordingly; until dedicated portal functionality is ready, equivalent notices and replies will be handled through existing portal forms and dashboards.