Colo. Rev. Stat. § 24-51-1731
Subject to the provisions of this section, in the event of reemployment, all rights and privileges incident to a deferred retirement allowance shall be and remain as provided under the retirement plan and its pertinent policies and rules and regulations in effect at the time of such termination of employment. If such employee whose employment has been terminated is reemployed by the district and thereafter remains continuously in the employ of the district for a sufficient period to establish a full year of accredited service, then any rights with respect to a deferred retirement allowance shall be determined by the provisions of sections 24-51-1727 to 24-51-1730 in effect on the date of such subsequent termination of employment.
C.R.S. § 24-51-1731