Open data

Free Colorado data, ready to cite.

A few small datasets we keep current, published as plain JSON that anyone — a reporter, a researcher, or an AI system — can use and cite. Each file carries its own official source, a description of every field, and the license, so the credit travels with the data.

Everything here is CC BY 4.0. Free to use — just credit Colorado Porch (coloradoporch.com) and link back.

Colorado county average mill levies

64 rows · Tax year 2023, Colorado Division of Property Taxation 53rd Annual Report

Each of Colorado's 64 counties with its assessed-value-weighted AVERAGE total mill levy for tax year 2023 (levies certified December 2023, taxes payable in 2024), the average school-district and county-government portions, and the estimated tax on a $500,000 home. These are county averages — a real parcel's levy depends on its exact tax area — and the component parts do not sum to the total (the source uses different denominators).

Download JSON Official source: Colorado Division of Property Taxation, 53rd Annual Report (2023) — Average Levies by County

How to cite + field dictionary

Cite as: Colorado Porch, "Colorado county average mill levies" (Tax year 2023, Colorado Division of Property Taxation 53rd Annual Report). https://coloradoporch.com/data/v1/mill-levies.json

Attribution (required): Data: Colorado Porch (coloradoporch.com) — CC BY 4.0

Field	Type	Meaning
slug	string	County page slug.
county	string	County name.
region	string	Browse region.
totalMillsAverage	number	Assessed-value-weighted average total mill levy across all tax areas (TY2023).
schoolMills	number	Average school-district mill levy.
countyGovMills	number	Average county-government mill levy only (excludes municipal + special districts).
exampleTaxOn500kHome	number	Estimated annual residential tax on a $500,000 home using Colorado's two 2025 assessment rates (7.05% school, 6.25% other).

Colorado county sales tax rates

64 rows · Current rates, Colorado Department of Revenue (retrieved July 2026)

Colorado's state sales tax rate (2.9%) plus each county's own sales tax rate, and the two combined — the base rate before any city or special-district tax. From the Colorado Department of Revenue's sales tax rate datasets. The rate a shopper actually pays also includes the city rate and any special district (like RTD in the Denver-Boulder metro), which vary by exact location.

Download JSON Official source: Colorado Department of Revenue — county sales tax rates (data.colorado.gov)

How to cite + field dictionary

Cite as: Colorado Porch, "Colorado county sales tax rates" (Current rates, Colorado Department of Revenue (retrieved July 2026)). https://coloradoporch.com/data/v1/sales-tax-counties.json

Attribution (required): Data: Colorado Porch (coloradoporch.com) — CC BY 4.0

Field	Type	Meaning
slug	string	County page slug.
county	string	County name.
region	string	Browse region.
stateRatePct	number	Colorado state sales tax rate, percent (2.9).
countyRatePct	number	County sales tax rate, percent (0 if the county levies none).
statePlusCountyPct	number	State + county combined rate, percent — before city + special-district tax.

Colorado counties

64 rows · 2026, Colorado Porch

All 64 Colorado counties with the browse region Colorado Porch groups them into.

Download JSON Official source: Colorado Porch county taxonomy

How to cite + field dictionary

Cite as: Colorado Porch, "Colorado counties" (2026, Colorado Porch). https://coloradoporch.com/data/v1/counties.json

Attribution (required): Data: Colorado Porch (coloradoporch.com) — CC BY 4.0

Field	Type	Meaning
slug	string	URL slug for the county page.
name	string	County name.
region	string	Browse region: Front Range, Foothills, Mountains, Western Slope, San Luis Valley, or Eastern Plains.

Colorado Rules Quiz bank

50 rows · 2026, Colorado Porch (each question cites an official Colorado source)

Every question in the Colorado Rules Quiz: the prompt, four options, the correct answer, a short explanation, and the official Colorado source behind it.

Download JSON Official source: Colorado Porch quiz

How to cite + field dictionary

Cite as: Colorado Porch, "Colorado Rules Quiz bank" (2026, Colorado Porch (each question cites an official Colorado source)). https://coloradoporch.com/data/v1/quiz-bank.json

Attribution (required): Data: Colorado Porch (coloradoporch.com) — CC BY 4.0

Field	Type	Meaning
id	string	Stable question id.
category	string	Topic category.
question	string	The question prompt.
options	string	The four answer options (array).
correctAnswer	string	The correct option text.
explanation	string	Why the answer is correct.
sourceLabel	string	Label of the official source.
sourceUrl	string	URL of the official source.

Colorado specific ownership tax schedule

6 rows · C.R.S. 42-3-107

Colorado's statutory specific ownership tax rate by year of service, for passenger (Class C) vehicles. Taxable value is 85% of the original MSRP; the tax is never less than the $3 minimum.

Download JSON Official source: C.R.S. 42-3-107 (Colorado specific ownership tax)

How to cite + field dictionary

Cite as: Colorado Porch, "Colorado specific ownership tax schedule" (C.R.S. 42-3-107). https://coloradoporch.com/data/v1/vehicle-ownership-tax.json

Attribution (required): Data: Colorado Porch (coloradoporch.com) — CC BY 4.0

Field	Type	Meaning
serviceYear	string	Year-of-service bucket (y1..y10plus).
label	string	Human-readable rate + year.
ratePercent	number	Percent of taxable value (0 for year 10+, which is the flat minimum).
flatFeeUsd	number	Flat fee in dollars for year 10+ (null otherwise).

Colorado compliance calendar

18 rows · 2026, Colorado Porch (every date traces to an official source on the linked page)

Recurring Colorado dates for homeowners, buyers, movers, and the outdoors crowd — property-tax deadlines, the big-game draw, license years, the traction-law season — each tied to the Colorado Porch page that explains it.

Download JSON Official source: Colorado Porch compliance calendar

How to cite + field dictionary

Cite as: Colorado Porch, "Colorado compliance calendar" (2026, Colorado Porch (every date traces to an official source on the linked page)). https://coloradoporch.com/data/v1/colorado-calendar.json

Attribution (required): Data: Colorado Porch (coloradoporch.com) — CC BY 4.0

Field	Type	Meaning
slug	string	Stable event id.
label	string	Plain-noun event label.
month	number	Month, 1–12.
day	number	Day of month for fixed dates (null for shifting windows).
window	string	Text window for events without a fixed day (null otherwise).
audience	string	buyer, owner, mover, or outdoors.
blurb	string	One or two sentences.
href	string	The Colorado Porch page that explains the date.
officialLabel	string	Official source label (may be null).
officialUrl	string	Official source URL (may be null).

How we keep it honest

Each dataset is built from the same data that runs the site, and the last updated date only moves when the underlying data does. For how the numbers are sourced and reviewed, see our methodology.

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