It is mentioned in the Qur'an (9:29) that,
Fight those who believe not in Allah nor the Last Day, nor hold that forbidden which hath been forbidden by Allah and His Messenger, nor acknowledge the religion of Truth, (even if they are) of the People of the Book, until they pay the Jizya with willing submission, and feel themselves subdued.
Why it is necessary for non-Muslims to pay Jizya? Although females, children and the poor are exempted from it I do not find any justification for others.
Please note that Muslims are required to pay Zakah but if they do not, there is no punishment for them doing so. But if any non-Muslim refuses to pay the Jizya he may lose all of his property, as mentioned in hadith (Muslim:19:4294):
If they refuse to accept Islam, demand from them the Jizya. If they agree to pay, accept it from them and hold off your hands. If they refuse to pay the tax, seek Allah's help and fight them.