I am a sub contractor do i have to pay worker's compensation?

Workers Comp varies from state to state but in general, if you are an employer you must pay for Workers Comp for your employees. Most large contractors require their subs to show evidence of Workers Comp coverage. This is because the insurance companies will charge the GC if they can't show evidence of all workers being covered under other policies. So in general, yes, sub contractors have to pay for Workers Comp.