Colo. Rev. Stat. § 31-31.5-306
Each employer shall pick up the mandatory employee contributions required under this part 3, to the extent allowed by the federal "Internal Revenue Code of 1986", as amended, and the contributions picked up shall be treated as employer contributions pursuant to section 414 (h)(2) of the federal "Internal Revenue Code of 1986", as amended, in determining their income tax treatment. The employer shall pay these employee contributions directly to the association, instead of paying such amounts to the members. Such contributions shall be paid from the same funds that are used in paying salaries to the members. Such contributions, although designated as employee contributions, shall be paid by the employer in lieu of contributions by the members. Members may not elect to choose to receive such contributions directly instead of having them paid by the employer to the plan. Employee contributions so picked up shall be treated for all purposes of this article 31.5, other than federal tax, in the same manner as employee contributions made before the date picked up.
C.R.S. § 31-31.5-306