<h1>GST enrolment for existing taxpayers requires Aadhaar authentication, document uploads, and electronic signature for provisional registration.</h1> Form GST REG-26 prescribes electronic enrolment for existing taxpayers, capturing identity, business constitution, principal/additional places of business, goods/services, bank accounts, and details of responsible persons; requires Aadhaar consent for authentication, upload of specified supporting documents, declaration, and an electronic signature. Successful validation of identity fields yields provisional registration with issuance of Form GST REG-25 and an Acknowledgement Reference Number; the portal validates PAN, Aadhaar, DIN and other identifiers and allows status tracking. Digital Signature Certificate or e-sign is required as per applicant type.