1 An estimate of the total cost of a new passport for your child/children can be obtained using the Estimate Your Costs calculator. 2  According to Family Vacation Critic, a website that features reviews of family-friendly hotels, resorts, destinations and attractions, the application fee for children below 16 is $80. The passports are valid for 5 years until the age of 16, at which time a new passport will be required. 2  The requirements needed when applying for a minor passport are as follows: evidence of citizenship, photo identification, parental consent, passport photo, application forms, and passport fees.