For tourists above 18 years of age either a Passport with a minimum of 6 months of validity or a Voter ID card or Driving License is required. For tourists below 18 years, a Passport or a birth certificate along with a school/college ID would be valid for a permit. You must carry at least 5 passport sized photographs with a plain background for each traveller. Note: Aadhaar card is not valid for a travel permit to visit Sikkim.