Colorado constitution
Article X
Section 3

(IV) If the valuation for assessment of a county as reflected in its abstract for assessment is more than five percent below the valuation for assessment for such county as determined by the study and if the state board of equalization fails to order a reappraisal, state equalization payments to school districts within the county during the year following the year in which the study was conducted shall be based upon the valuation for assessment for the county as reflected in the county's abstract for assessment. The board of county commissioners of such county shall impose in the year in which such school payments are made an additional property tax on all taxable property in the county in an amount sufficient to repay, and the board of county commissioners shall repay, the state for the difference between the amount the state actually paid in state equalization payments during such year and what the state would have paid during such year had such state payments been based on the valuation for assessment as determined by the study.