Aadhaar authentication requirement for GST registration changes verification steps and prescribes revised deemed approval timelines. Applicants (other than those notified under section 25(6D)) opting for Aadhaar authentication must undergo it and the application date is the date of authentication or fifteen days from Part B submission, whichever is earlier. If Aadhaar authentication is not completed or not opted for, registration requires physical verification of business premises, though the proper officer may instead verify documents with written reasons and Joint Commissioner approval. Time limits for officer action are set at three working days after successful Aadhaar authentication, the proviso-prescribed period after failed authentication, twenty-one days if not opted, and seven working days after receipt of clarifications.