Sources

Your property tax bill (Arapahoe)

On the home page, the levy breakdown can load taxing authorities from your parcel PIN using offline county data mart-style exports joined with Colorado property-tax entity data where matching is safe. Loading a stack only reads this site's bundled data — no live requests to the county.

Check the numbers yourself (no code)

Use the home card See how Arapahoe County displays your data or the county parcel record and online levy table; compare to what the app shows after you load by PIN or add entries with Add tile.

1. Open Search Residential, Commercial, Ag and Vacant (opens in a new tab) (or the peer links on the home card) and note the PIN on the parcel record.
2. Open Tax District Levies for that parcel. Compare each taxing authority and its mills to the app after you load by PIN — they should align.
3. The tool may omit one assessor fee entry that appears in some exports but not on the online levy table (see methodology below). School districts, cities, and counties often will not appear in optional state "special district" directories even though they are on your bill.

How matching works

• Address and PIN: Search uses situs house number (plus optional number suffix), street name with direction and street type stripped for matching, and optional unit. Incomplete or lightly misspelled street types (for example stree for street) and close street-name typos are resolved against other roads at the same house number; when several streets are plausible, the form offers choices. You can also paste a parcel PIN or assessor AIN into the address or parcel-id field. Search or Enter from any field. Above the form, an Own / Rent switch (default Own) is self-declared: we do not infer tenure from the parcel. The same switch stays on the locked report so you can flip the lens without starting over. One address can match many parcels; when several match, tap the row you want (whole row is the control). A short glossary line explains real property vs. business personal property once above the list — not on each row. Rows show the county situs street line and a second line with city, state, and ZIP from the Main Parcel export (the county file with parcel address details). Business personal property accounts can appear in that list when they share a street address with Real property. On the locked report, Switch account type appears only when that mix is present (not for all-Real multi-unit lists such as condo units). Those accounts keep owner, situs, values, and the property-tax breakdown for their tax district; building, land, sale, permit, and comparable-properties tools stay with Real parcels. Equipment accounts can open a county Notice of Valuation PDF when an AIN is in the pin map. Nothing is sent to our servers; address fields are length-capped in the browser.
• Taxing authority group (TAG): Your parcel maps to a county taxing authority id (TAG). The county's online levy table uses the same id — it is not a private per-parcel serial number.
• Property classification: In Property details, under the county-record panel, we show the assessor's property-class description from the county data. A paper notice may still say Residential or Commercial for the same parcel; see Property classification in the Glossary.
• District contact vs tax IDs: Levy tile mills and tax-entity linkage come from one join path (county tags matched to DOLA property-tax entities). Website and mailing contacts come from a separate state LG directory filtered to districts on shipping county stacks (Arapahoe and Douglas today). Bill LG ID and directory LG ID can differ — public mail often reflects administration or management, not a single tidy join. When IDs align, that is the strongest link; when only the name is fuzzy or IDs differ, contact still appears with that explanation. See LG ID.
• Assessor fee: Some mart exports include an assessor fee code that does not appear on the online levy table. The PIN loader omits that row so the list matches the table you can copy from.
• Geography on fuzzy name matches: Similar district names exist across Colorado. When a name-only match is needed, the directory path prefers districts tied to Arapahoe so the wrong county's contact information is less likely to win.

Property details methodology

After a PIN load, Property details show county-record fields joined from the Assessor Data Mart (legal, ownership, land, buildings, sales, permits when present), including state use, subdivision, and tax roll when the export has them. Neighborhood name and code come from the Assessor Open GIS Parcels (opens in a new tab) layer (PIN join; code and name only), not from the Main Parcel CSV, which has no neighborhood column. We do not guess neighborhood from subdivision name. Empty cells use No data found with a short report link.

• Own vs Rent lens: Choosing Rent keeps the same tax account and property-tax bill breakdown (the same individual bill entries; the on-screen levy stack). It emphasizes tax pressure for the entire property (annual and monthly estimates). When we can resolve a dwelling count N from county land-line UB units, or from a duplex / triplex / fourplex building type, or from a typical single-dwelling account, we also show a crude equal split (annual ÷ N and that amount ÷ 12), and the dollar amounts on those bill entries (and metro estimates when shown) use that same per-unit share, then show as monthly figures labeled /mo so they read like rent. Metro headline wording in Rent mode frames shares as a percent of estimated monthly property tax (not of rent). That split is an estimate only: it assumes every unit bears the same share, may attribute some non-residential tax on mixed-use parcels to dwellings, and is not a lease line or proof that rent passes tax through one-for-one. When N is unknown we show whole-property totals only (including bill-entry $, still monthly in Rent) and say we do not know how many units share the account (not "homes," so commercial Real accounts read cleanly). Own mode keeps annual whole-account dollars. Rent mode tones down owner tools (comparable-properties PDF, owner mailing rows) and tucks dense sale / building / land tables under a disclosure. The Own | Rent switch and Rent dashboard are not offered for business personal property accounts (equipment tax is not a renter lens). Renting is not the same as commercial assessment class.
• Value labels use the data mart assessment year (as on the county parcel page), not the tax year used for the levy roll (the county's certified mill rates for that billing year). When those two years differ, the values section notes both, and the assessment-year summary tile shows the tax year as a secondary line.
• Assessed school value is the taxable value school districts use for the school portion of your property tax bill. It is not a mart column. For improved residential property from 2025 onward, the app computes it with the Colorado Department of Property Taxation (DPT) school assessment rate (7.05% for 2026) on appraised building and land, rounded the way the county parcel page does. Residential parcels use a state use code starting with 1 (a county classification for how land is used). Non-residential property does not show a school assessed row.
• Assessed value totals come from the mart total assessed figure. Building and land columns follow the county pattern. Residential local splits use the DPT local rate on land (6.8% for 2026 after the temporary reduction on the first $700,000 of actual value; building = total minus that land split). Non-residential splits allocate the mart total in proportion to appraised building and land. The percent next to an assessed row shows which rate turned appraised value into assessed value, the figure mill rates use on your property tax bill. For Real property, labels follow the county's state use code when that code maps cleanly to a DPT chart row (for example commercial 25%/26%, industrial 26%); exempt and other unmapped codes omit the parenthetical rather than invent a percent. Business personal property uses the Colorado personal-property assessment rate for that assessment year (26% for 2026; 27% for 2025; 25% from 2027), not the Real state-use chart. Logic lives in src/lib/parcelAssessmentRates.ts (display) and the build script (bundled shards).
• Prior-year assessed value: Property details and the values table use the mart for this assessment year's actual and assessed figures.

  COUNTY DATA GAP

  We searched published county and state sources for prior-year actual and assessed values, including the Assessor Data Mart Main Parcel Table (opens in a new tab). That table has this assessment year's figures only. None of those sources include prior-year assessed history in a bulk table we can obtain. Per the assessor's office, there is no historical information available on the public website. Individual prior-year figures may be available only by contacting the assessor's office directly. Without those figures, there is no valuation trend to show. Subject sale history on the parcel record still comes from Parcel Transfer Information. Mill-rate year-over-year dollar lines still use this year's assessed value for both years when last year's mills are known.
• Ownership type uses legal-party owner rows: one owner keeps that row's type; when every owner is Individual, we show Joint Tenancy to match the usual county parcel-page label for co-owners (vesting is not in the mart, so other arrangements cannot be told apart).
• Sale Book Page opens Arapahoe Clerk and Recorder public search (same pattern as the county parcel page). Some older filings return no document there — that can happen on the county site too.
• Comparable properties (often called comps) uses the parcel's AIN when available. When county hosting is limited, the home summary tile shows COUNTY DATA GAP with a short status; the whole tile opens the full explanation (the PDF icon is a visual cue), and includes a link to try the county download if your value changed. The in-page comps grid is demo-only today (Try demo property); row help is grounded in the county Comp Sheet Layout and Time Adjusted Sales Prices (opens in a new tab) explainer.

  COUNTY DATA GAP

  The county comparable properties PDF (opens in a new tab) (FileDownload.ashx on the parcel record site) often returns no file found. Per the Assessor's office: The county site posts comps for the current year only. If your value did not change from 2025 to 2026, no new comps grid appears online. The county also stated it would no longer make the 2025 comps available. Those prior comps still apply, but the county download does not provide them. The office expects comps online again for every parcel after 2027 valuation postcards, in late April or early May.
• Notice of Valuation for business personal property uses the same AIN pattern on personalpropertysearch.arapahoegov.com (FileDownload.ashx?AIN=…). That PDF is the county notice for the equipment account, not a comps grid. Real-property parcelsearch FileDownload does not serve these notices. The county compare card also links the account details page (Details.aspx?AIN=…) on that same host. On the home dashboard, business personal property keeps the short property panel and totals-only values table together in the property column; Real accounts still place the longer values / sale / building / permit tables below the levy grid.

How current is the data?

The app serves static data, not live county or state APIs. The UI shows "County data current as of …" from the date maintainers recorded when they last downloaded a fresh Assessor Data Mart (opens in a new tab) extract (often updated about weekly), not from the last time the offline rebuild scripts ran. Maintainers download tables such as Main Parcel Table and Tax Authority Groups and Tax Authorities as CSV from that portal and join them offline when refreshing bundled data; looking up a PIN does not call a live Data Mart API. Neighborhood name and code on Property details also join from the Assessor Open GIS Data (opens in a new tab) Parcels download (local FileGDB; PIN + neighborhood fields only into public JSON). DOLA Property Tax Entities (opens in a new tab) and the Special District Mapping Project (opens in a new tab) feed tax-entity and contact matching when mills or IDs change. Maintainers refresh Property Tax Entities as a statewide CSV (see README): on the DOLA portal, select certifying county only and search — do not filter by local government type. The build filters rows by certifying county; replacing the CSV does not change bundled levy JSON until rebuild. Metro rates follow the annual mill levy form, not the weekly mart cadence. How maintainers download, stage, and rebuild: repository README (opens in a new tab).