Colo. Rev. Stat. § 31-12-503
When the governing body of such municipality levies a tax upon the property within such municipality for the purpose of paying such indebtedness or any part thereof or interest thereon, such governing body may levy a tax at the same rate and for the same purpose on the land so disconnected. The county treasurer shall pay over to such municipality all moneys collected by the treasurer on account of such tax, to be applied only to the payment of such indebtedness. In case the owner of any land so disconnected pays off and discharges a portion of such indebtedness equal in amount to the same proportion of the indebtedness which the valuation for assessment of the land bears to the entire valuation for assessment of all the property subject to taxation for the payment of such indebtedness, calculated according to the last assessment previous to such payment, said land is exempted from further taxation to pay such indebtedness. Upon such payment being made, the canceled bonds or other evidences of payment of such portion of said indebtedness must be deposited with the treasurer of such municipality, and a certificate shall be given by the treasurer stating that such payment has been made.
C.R.S. § 31-12-503
This section is similar to former § 31-8-603 as it existed prior to 1975.