Revocation of registration allows application subject to furnished returns and officer discretion to revoke or reject. Rule 23 sets the procedure for revocation of cancellation of registration by allowing the cancelled registrant to apply in FORM GST REG-21 within the prescribed period, provided returns and dues are filed and paid where cancellation arose from non-filing. The Commissioner may extend the period for sufficient cause. The proper officer must either revoke the cancellation by order in FORM GST REG-22 or reject it by order in FORM GST REG-05 after issuing a show cause notice in FORM GST REG-23 and considering the applicant's reply in FORM GST REG-24 within the specified timelines.