Key Takeaways
Proposition NN is on the November 3, 2026 ballot, referred by the Colorado legislature through Senate Bill 26-135.
If approved, it would let the state keep and spend revenue above the TABOR (Referendum C) cap for K-12 education and homestead-exemption reimbursements.
It would not change your property tax rate, your assessment, your exemptions, or your appeal deadline.
Its main effect would be on your TABOR refund, not your property tax bill.
You can lower your Colorado bill now by appealing your assessment by June 8 or claiming exemptions you qualify for.
What Is Proposition NN?
Colorado Proposition NN is a legislatively referred state measure on the November 3, 2026 ballot that would let the state keep and spend tax revenue it collects above the TABOR cap, rather than refunding it. It is not a change to your property taxes.
To understand it, start with TABOR. The Taxpayer's Bill of Rights, a 1992 constitutional amendment, limits how much revenue the state can keep and requires it to refund the excess to taxpayers. The Referendum C cap sets that current limit. When the state collects more than the cap allows, the extra money goes back to you as a TABOR refund.
If approved, Proposition NN would let the state retain and spend that above-cap revenue on K-12 public education and to cover its homestead property-tax exemption reimbursements, an amount roughly the size of state K-12 spending. The measure was referred to voters by the General Assembly, with Senate Joint Budget Committee chair Sen. Jeff Bridges as prime sponsor. It is the only measure referred to the November 2026 ballot by the legislature, and you can read the instrument on the official Senate Bill 26-135 page.
Does Proposition NN Change Your Property Taxes?
No. If approved, Proposition NN would not change your residential assessment rate, your home's actual value, your exemptions, or your appeal deadline. It sits on the state's revenue and refund side, not in the chain that sets your property tax bill.
One property-tax touchpoint is worth knowing...
The retained revenue would help fund the state's reimbursement to local governments for the senior and disabled-veteran homestead exemptions, which keeps that exemption program funded. That is a funding mechanism, not a change to the exemptions themselves.
The measure would change your TABOR refund. According to a Common Sense Institute analysis, Prop NN would increase state spending by $329.9 million in FY 2027 and $521 million in FY 2028, with retained revenue also covering homestead property tax exemption reimbursements. Nothing you need to do about your tax bill changes because of this measure.
Proposition NN vs. Proposition HH: Clearing Up the Confusion
Many Coloradans confuse Proposition NN with Proposition HH, and the two are different. Proposition HH, on the 2023 ballot, was a property-tax and TABOR measure that voters rejected, so it never took effect. Do not treat it as current law.
Proposition NN is an education-funding and TABOR measure, not a property-tax measure. The table below sums up the difference.
Measure | Year | What It Addresses | Status |
|---|---|---|---|
Proposition HH | 2023 | Property tax reductions plus TABOR cap changes | Rejected by voters; never took effect |
Proposition NN | 2026 | TABOR cap for K-12 education and homestead reimbursements | On the November 3, 2026 ballot |
What Proposition NN Would Cost Taxpayers
Because Proposition NN is on the ballot and not yet law, any cost figures describe what would happen if voters approve it. The impact would land on refunds, not tax bills.
According to nonpartisan fiscal analysis, it would reduce TABOR refunds by $136.1 million in FY 2026-27 and $969.7 million in FY 2027-28, and the average Colorado taxpayer would forgo about $7,300 in refunds over the next decade. Per-taxpayer amounts are smaller in a single year.
Per a draft legislative council explainer, a taxpayer earning $100,000 a year would see their 2027 TABOR refund reduced by about $28, or $56 for a joint filer.
Supporters say the measure funds schools without raising tax rates. Opponents call it a de facto cut to refunds. Both framings point to the same mechanism: the state would keep money it now returns.
Why Colorado Homeowners Are Watching Their Tax Bills
Colorado homeowners are already anxious about rising bills. In our 2025 National Homeowner Survey, 85% of Colorado homeowners worry about significant increases in their annual property tax bills, the highest state-level concern we measured.
That anxiety stems from the assessment cycle. Colorado reassesses property values in odd years, and the 2025 reassessment set the values used for 2025 and 2026 while Front Range home prices climbed sharply. Prop NN doesn't affect any of that.
Your bill comes from three parts: your home's actual value, the assessment rate applied to it, and your local mill levy. Colorado uses two residential assessment rates, one for school districts and one for other local governments. Mill levies vary by taxing district and are set each December locally, so confirm yours with your county. For a local example, see how Colorado county property taxes work in Douglas County.
How Much Are You Over Paying?
How to Lower Your Colorado Property Tax Bill Right Now
No matter how you vote on Proposition NN, you can still act on your own bill. Most homeowners never do. In our 2026 National Homeowner Survey, 74% of homeowners have never appealed their property tax bill, and 57% didn't know they had the right to.
Start with an appeal. Colorado's real-property protest deadline is June 8, and your county mails your Notice of Valuation by May 1. An appeal challenges your home's actual value, and in Colorado your own appeal cannot raise it, so there is no downside to filing. If your value dropped and you are unsure whether to act, here is how a property tax appeal works and why you should appeal even if your value dropped.
Next, claim every exemption you qualify for. The senior homestead exemption removes up to $100,000 of your home's actual value if you are 65 or older and meet the ownership rules, and applications are due July 15. Disabled veterans can qualify for the same benefit, and a state deferral program can ease cash flow. Learn more in our Colorado Senior Property Tax Exemption guide or browse property tax exemptions by state.
Unsure Which Exemptions You Qualify For?
Commercial and investment property owners feel the same value pressure and can appeal too. The mechanics are similar, and the savings can be larger.
How Ownwell Can Help
At Ownwell, we handle your Colorado property tax appeal end to end. We build a comparative market analysis, file with the County Board of Equalization, represent you at hearings, and track your results.
In Colorado, we charge a 35% contingency fee with no upfront cost, so you only pay when we save you money. We do not file exemptions in Colorado, but our guides walk you through those on your own. Across more than 1 million appeals we have managed, 88% of our customers received a reduction.
Frequently Asked Questions
Does Proposition NN raise my property taxes?
No. Proposition NN would not change your property tax rate, assessment, or exemptions; its impact falls on your TABOR refund rather than your tax bill.
Is Prop NN the same as Proposition HH?
No. Proposition HH was a 2023 property-tax and TABOR measure that voters rejected, while Proposition NN is a 2026 education-funding and TABOR measure that does not change property taxes.
Will Prop NN reduce my TABOR refund?
If voters approve it on November 3, 2026, nonpartisan estimates project smaller refunds in the years ahead, as covered in the cost section above.
When do Coloradans vote on Proposition NN?
Coloradans vote on Proposition NN on November 3, 2026, as a legislatively referred measure placed on the ballot through Senate Bill 26-135.
If Prop NN doesn't change my property tax bill, how can I lower it?
You can appeal your assessment by the June 8 deadline and claim any exemptions you qualify for, both of which we cover in the section on lowering your Colorado bill.
