Is a sixteen-year-old obliged to inform the transport official of his age if the official believes him to be under fifteen, and thus pay a lower fare?

Whoever takes money unlawfully must inform its owner; otherwise, he is consuming ill-gotten gains. This is based on Allah's saying: "And do not consume your properties among yourselves through falsehood," and the Prophet's (peace be upon him) saying: "The property of a Muslim is not lawful except with his willing consent." If the owner of the money cannot be identified, then the money should be given in charity with the intention of purifying oneself from ill-gotten gains.