C.R.S. § 42-3-111

(1) The annual specific ownership tax shall attach and apply to motor vehicles, trailers, semitrailers, or trailer coaches operated upon the highways of this state for the registration period within which it is levied and collected. (2) Payment of an annual specific ownership tax on a trailer coach to the authorized agent of a county of this state in which the situs of the trailer coach is established at the time of registration for all of a registration period shall constitute the entire tax payable on such vehicle.