Both the Colorado Constitution and state statutes are subject to amendment by legislatively referred and citizen-initiated measures. The process is governed by the Colorado Constitution and state law.[1]
Legislatively referred measures
The Colorado General Assembly may refer constitutional measures to the voters with a two-thirds vote of both houses, and may refer statutory measures to the voters with a majority vote of both houses. A constitutional measure requires 55 percent of the votes cast in an election to pass, except when a proposed measure repeals rather than changes part of the constitution, in which case a simple majority of votes is required.[2] While the General Assembly has the authority to change the state statutes during legislative session, the Taxpayer's Bill of Rights (TABOR) requires that proposed tax increases receive approval from voters in order to take effect. The General Assembly submitted its first measure to Colorado voters in 1880.
Citizen-initiated measures
Any Colorado resident may place a constitutional or statutory measure on the ballot. To place a measure on the ballot, proponents must collect the number of signatures equal to 5 percent of the total number of votes cast for the Secretary of State at the previous general election. Additionally, to place a constitutional measure on the ballot, at least 2 percent of registered voters' signatures in each of the state's 35 senate districts are required. The constitutional measure must also receive at least 55 percent of all votes cast to pass, unless a proposed measure repeals rather than changes part of the constitution, in which case a simple majority of votes is required.[3] The use of citizen-initiated measures for constitutional and statutory changes was voted into law in 1910 and became available in 1912.
Process for placing a citizen-initiated measure on the ballot
The multi-step process for placing a citizen-initiated measure on the ballot includes the submission of a proposed initiative; a review and comment hearing on the proposal with the Office of Legislative Legal Services and the Legislative Council Staff; a hearing with the Title Board to set the single-subject title; and verification of collected signatures by the Secretary of State. These steps are outlined on the Secretary of State's and the Colorado General Assembly's websites.
Even- and odd-numbered year elections
State law clarifies the types of proposals that may appear on a statewide ballot in odd-numbered years.[4] Odd-year election proposals are limited to state matters arising under TABOR. These types of proposals include a new tax, a tax rate increase, an extension of an expiring tax, a tax policy change directly causing a net revenue gain, and emergency taxes. They also include the creation of multiple-year fiscal obligations or debt, an increase in the assessment rate for a class of property, the weakening of a state limit on spending, and voter-approved revenue changes. State law does not limit the types of proposals that are eligible for the ballot in even-numbered years.
Numbering and lettering for ballot measures
Statewide citizen-initiated measures are numbered, while those that are legislatively referred are lettered. Table 1 provides further detail on the numbering and lettering schedule for statewide ballot measures.
Table 1: Ballot Measure Numbering and Lettering Schedule [1]
| Type | Amendment (Constitutional) | Proposition (Statutory) |
|---|---|---|
| Citizen-initiated | 1 to 99 (last used: 80) |
100 to 199 (last used: 131) |
| Legislatively referred | A to Z (last used: K) |
AA to ZZ (last used: KK) |
Source: Section 1-5-407, C.R.S.
[1] Parenthetical notes indicate the alphanumeric designation last used as of the 2024 election.
- [1] Colo. Const. art. V, § 1 and Sections 1-40-101, et seq., and 1-41-101, et seq., C.R.S.
- [2] Colo. Const. art XIX, § 2.
- [3] Colo. Const. art. V, § 1.
- [4] Section 1-41-102, C.R.S.