For children under the age of 3 (who are admitted to Disney parks for free), Disney Cast Members rarely ask for official proof of age like a birth certificate. The "honor system" is the standard practice, as Disney values guest experience over the potential friction of "playing detective" at the gates. However, if a child appears significantly older (e.g., a 5-year-old trying to pass as 2), a Cast Member may politely inquire about their age. If you are worried, keeping a digital photo of your child's birth certificate or passport on your phone is a "pro-tip" for 2026. For "Adult" versus "Child" (ages 3–9) tickets, the system is mostly self-policing through the My Disney Experience app. However, for "Junior" tickets (ages 12-17) at international parks like Tokyo Disney, proof of age or a student ID may be required more strictly. At U.S. parks, once a child hits 10, they are considered an "adult" for pricing, and if there is a major discrepancy, Disney reserves the right to ask for verification to ensure the correct fare is paid.