Amendment 87 Faces $3.6M Dark Money Challenge

Aspen —Ian Silverii calls it “pretty outrageous.” He’s talking about the idea that Colorado’s wealthiest residents — billionaires, millionaires, and the state’s largest corporations — should keep paying the exact same flat tax rate as everyone else. For Silverii, a member of the Protect Colorado’s Future Coalition, that status quo is the problem. He wants Amendment 87 to fix it by replacing the flat tax with a graduated income tax system.

On paper, the proposal looks straightforward. Amendment 87 would raise the tax rate for incomes above $500,000 and lower taxes for anyone earning less. The goal is to generate an additional $2.7 billion for the state to spend on healthcare, education, and childcare. To get there, the campaign needed to mobilize voters. As of the October 6 filing deadline with the Colorado Secretary of State’s Office, supporters had disclosed around $1 million in spending. That money came from small donations ranging from $5 to $500 from approximately 300 individual Colorado residents, plus contributions from dozens of nonprofits with local and state ties.

But the opposition isn’t playing with small change. Let’s do the math. The groups fighting Amendment 87 disclosed more than $3.6 million in spending by the same deadline. While a couple dozen individual Coloradans did donate, the vast majority of that cash came from large checks written by groups that don’t disclose their donors. Silverii labels this “dark money.” In practice, it flows through conservative political advocacy groups registered as 501(c)(4) organizations, which are exempt from donor disclosure requirements.

Leading the charge against the amendment is Advance Colorado, a nonprofit founded in 2020 by former Republican Governor Bill Owens. The group doesn’t list its donors publicly, but reporting from outlets including the Denver Post has revealed major support from billionaire Phil Anschutz. Advance Colorado is deeply embedded in this election cycle; it is connected to roughly half of the 14 ballot measures before voters. That includes Proposition 136, a direct countermeasure to Amendment 87. Prop 136 proposes to maintain Colorado’s flat tax rate of 4.4% within the Taxpayer Bill of Rights.

Here’s where it gets legally tricky. Kristi Burton Brown, Advance Colorado’s executive vice president, argues that voters should focus on what the policy does, not who funds it. She has also accused Amendment 87 supporters of accepting large contributions, though her specific accusations in the available reporting remain focused on the funding disparity. The real conflict arises if both measures pass. Prop 136 maintains the flat rate. Amendment 87 creates a graduated rate. According to the official voter information packet, if both pass with a 50% majority vote, it could create legal questions that would have to be answered by a court.

For locals, the stakes are tangible. Amendment 87 aims to shift the burden away from middle-income earners and toward high earners, funding critical services. The opposition, backed by millions in undisclosed funds, seeks to preserve the current flat structure. The fight isn’t just about tax rates; it’s about transparency. Who is paying to keep the system as it is? And who is paying to change it? With $3.6 million in dark money versus $1 million in disclosed support, the financial imbalance is stark. Voters in November will decide not just the tax code, but which version of Colorado’s fiscal future they believe in.