[nraf]

The jizya was payable by non-Muslims dhimmis living in an Islamic state. I don't know of any requirements that had to do with participating in the military, as there were non-Muslims citizens who fought alongside the Muslims (e.g. Christians battling in the Ottoman armies). The only thing I've heard is that the jizya is to refunded if the Muslims fail to defend the non-Muslims paying jizya if they're attacked. Not sure how accurate that is though.