Revocation of cancelled GST registration window extended; clarifies applicability and conditions for further 30-day statutory extensions. Where the due date to apply for revocation of cancellation of registration fell between 1 March 2020 and 31 August 2021 for registrations cancelled under clause (b) or (c), the filing deadline is extended to 30 September 2021. The extension applies regardless of application status (not filed, pending, rejected, on appeal, or rejected on appeal), and officers and appellate authorities must process or decide matters taking the extended timeline into account. The circular further clarifies how this extension interacts with the statutory proviso permitting additional administrative extensions of the initial filing period.