Sources for 2026 Statewide Ballot Measure Briefs: Amendment 87 and Proposition 136

Amendment 87 – Graduated Income Tax 

1. Paul J. and Solomon R. Lawmakers finish drafting Colorado’s budget with final round of major cuts to address roughly $1.5 billion shortfall. Colorado Sun. (April 2026).  
2. Colorado Secretary of State. Results for Proposed Initiative #195. (2026).  
3. Legislative Council Staff. Individual Income Tax. Colorado Online Tax Handbook, Colorado General Assembly. (2026).  
4. Ag Decision Maker. Understanding Progressive Tax Rates. Iowa State University Extension and Outreach. (2022).  
5. Legislative Council Staff. Fiscal Impact Statement. Initiative 195. (2026). 
6. U.S. Census Bureau. 2024 American Community Survey. (2024). 
7. U.S. Census Bureau. (2024). 
8. U.S. Census Bureau. (2024). 
9. U.S. Census Bureau. (2024). 
10. U.S. Census Bureau. (2024). 
11. Roeder A. SNAP Lifts Families Out of Poverty, Bolsters Local Economies, Expert Says. Harvard T.H. Chan School of Public Health. (2025).  
12. Legislative Council Staff. Fiscal Impact Statement. Initiative 195. (2026).  
13. Legislative Council Staff. Individual Income Tax. (2026).  
14. Pethokoukis J. Study: Making a Tax Code More Progressive Hurts Economic Growth. American Enterprise Institute. (2013).  
15. Colorado Secretary of State. Proposed Initiative 2025-2026 #195: Final Text. (2026).  
16. Caven E. The Progressive Income Tax. Advance Colorado. (2026).  
17. Goodland M. What Happens If Voters Pass Colorado's Two Competing Income Tax Measures? Colorado Politics. (2026).  
18. Colorado Secretary of State. Results for Proposed Initiative #195. (2026).  
19. Colorado General Assembly. Ballot Information Booklet (Blue Book).  
20. The Colorado Health Foundation. Local Ballot Measure Tracker. (2026).   

Proposition 136: Income Tax Rate Cap 

1. Anderson C. and Hernandez J. Colorado Initiative 232: Income Tax Rate Cap. Common Sense Institute Colorado. (2026).  
2. Gamm E. and Kaminsky R. How Initiative #195’s Progressive Tax Structure Would Affect Colorado’s Economy. Common Sense Institute Colorado. (2026).  
3. Legislative Council Staff. Fiscal Summary. Initiative 232. (2026).  
4. McCauley B. Signatures submitted for Colorado income tax cap measure that competes with proposed graduated income tax initiative. Ballotpedia News. (2026).  
5. Gamm E. and Kaminsky R. How Initiative #195’s Progressive Tax Structure Would Affect Colorado’s Economy. Common Sense Institute Colorado. (2026).  
6. Denver Metro Chamber of Commerce. Denver Metro Chamber of Commerce Announces 2026 Prospective Colorado Ballot Initiative Positions.  
7. The Gazette Editorial Board. EDITORIAL: Progressive’ tax hike would fleece Colorado. (2026). The Denver Gazette.  
8. Ballotpedia. Colorado establish 4.4% cap on individual and corporate income tax rates initiative. (2026).  
9. Paul J. Colorado voters will decide whether to cap income tax rate, put “right to hunt and fish” in state constitution. The Colorado Sun. (2026).  
10. Goodland M. What happens if voters pass Colorado’s two competing income tax measures? Colorado Politics. (2026).  
11. Colorado General Assembly. Ballot Information Booklet (Blue Book).  
12. The Colorado Health Foundation. Local Ballot Measure Tracker. (2026).