Islamically, Hajj is obligatory (fard) only for those who have reached puberty (bulugh), are of sound mind, and meet other conditions of obligation. A child who has not reached puberty can perform Hajj, and it is valid as a voluntary (nafl) act of worship, but it does not count as fulfilling the obligatory Hajj — they must perform Hajj again after reaching puberty. The Prophet Muhammad (peace be upon him) confirmed this when a woman lifted her child and asked if the child could perform Hajj.
Saudi Arabia sets its own administrative requirements which may include minimum ages for visa issuance. Children must be accompanied by parents or legal guardians and should be included in the family's Hajj application. Some countries have their own age restrictions for Hajj registration.
There is no maximum age limit in Islamic law for Hajj. However, Saudi authorities may issue health advisories or guidelines for elderly pilgrims. Elderly individuals should obtain thorough medical clearance before applying. If a person is too old or ill to perform Hajj themselves, they may delegate someone to perform Hajj on their behalf (Hajj badal), provided they have the financial means. This proxy must have already performed their own obligatory Hajj first.