MSME classification thresholds set composite investment and turnover criteria with online Udyam Registration and self-declaration. Enterprises are classified by composite investment and turnover ceilings into micro, small and medium categories; classification aggregates units with the same PAN and GSTINs. Udyam Registration is an online, self-declaratory process issuing a permanent Udyam Registration Number and an e-certificate, with investment linked to Income Tax Returns and turnover excluding exports. Aadhaar, and where applicable PAN and GSTIN, are required; prior registrations must transition to Udyam and registered enterprises must update information or face suspension, with single-window facilitation and grievance procedures provided.