Is it obligatory to remit the entire profit from airline tickets, obtained through cooperation with other companies, to the company, or is it permissible to share a portion of this profit with the company? And in the latter case, what is the Sharia-compliant ratio for each party?

It is not permissible for an employee to take anything other than his salary. Any profit he gains in his work is the company's right, and an employee taking from it is considered a betrayal. If an employee takes something other than profit, which the client paid him personally, this is called "gifts to workers," and it is not permissible Islamically except with the employer's permission, due to the Prophet's (peace be upon him) saying: "Gifts to workers are ill-gotten gain (ghulul)." Accordingly, it is not permissible to take any profit obtained from the client through airline tickets from other companies unless with the tourism company's permission. We advise the Muslim to seek a job from which he can earn a lawful livelihood, because work in tourism companies often involves directly committing a forbidden act or assisting in it.