Final return requirement: persons with cancelled GST registration must file FORM GSTR-10 within the prescribed extended period. Notifying persons whose registrations were cancelled on or before 30 September 2018 as a class obliged to furnish the final return in FORM GSTR-10, and prescribing that such final returns may be furnished up to 31 December 2018, thereby setting the procedural deadline for compliance following cancellation of registration.