When traveling abroad with a child, the child must have his/her own passport, with a birth certificate serving as a valid identity document for the child. 

If a person under the age of 16 travels with his/her own passport while accompanied by parent(s), he/she must also carry a birth certificate to confirm the parent's status.  

On domestic flights within Kazakhstan, an electronic birth certificate (accessible through the digital document service) is accepted for identification of children under 16 years of age who are citizens of the Republic of Kazakhstan, only if they are traveling with their parents (legal representatives).

If citizens of the Republic of Kazakhstan under the age of 16 are traveling as unaccompanied minors or are accompanied by authorized persons who are not their parents (legal representatives), they must carry a paper identity document (birth certificate) or a foreign passport of a citizen of the Republic of Kazakhstan for check-in and boarding.

When children or underage citizens of the Republic of Kazakhstan travel with adults, the airline may require the child's birth certificate and documents proving kinship or legal rights to accompany the child.  

If an adult accompanying the child is not the parent or legal guardian, they should have a notarized power of attorney, in either paper or digital format, confirming their right to accompany the child. 

Travelers going abroad should familiarize themselves with the host country's requirements for underage children, as they may need a separate passport to stay in the host country.