While filling out the NEET UG application form, candidates must provide several documents and details. These include a scanned passport-size photograph, scanned signature, Class 10 certificate (for date of birth verification), Class 12 details or marks, valid identity proof such as Aadhaar card or passport, and category certificate if applicable (SC/ST/OBC/EWS/PwD). Candidates must ensure that the photograph and signature meet the size and format specifications provided by NTA. Providing incorrect or mismatched documents may lead to rejection of the application.