Best judgment assessment for return non-filing may follow notice; subsequent valid return can withdraw the assessment. Where a registered person fails to furnish a statutory return, issue FORM GSTR-3A electronically requiring return within fifteen days; if the return remains unfurnished the proper officer may make a Best Judgment assessment and issue FORM GST ASMT-13, upload the summary in the recovery form, and rely on outward supply statements, auto populated data, e way bills or inspection material. A valid return filed within the prescribed cure period after service of the assessment order will deem the assessment withdrawn; otherwise recovery and protective measures including provisional attachment and registration cancellation may follow.