What is an APN (Assessor’s Parcel Number)?
An APN — Assessor’s Parcel Number — is the unique identifier a county assessor assigns to a single parcel of land for property-tax purposes. In Maricopa County it’s an 8-digit number written as ###-##-### (for example, 301-45-678). Every parcel has exactly one APN, which is how permits, deeds, ownership, and sales records all tie back to the same piece of land.
The format encodes location: in Maricopa County the first three digits are the map book, the next two the map page, and the last three the parcel on that page. Other Arizona counties use their own digit patterns, but the idea is the same — one permanent number per parcel.
An APN is not an address. A single parcel can have several addresses (think a strip mall or an apartment complex), and addresses change while the APN stays fixed. That’s exactly why property data is keyed on the APN, not the street address — it’s the reliable join between a building permit, the owner of record, and the property’s sales history.
At PlumbIntel we normalize APNs (stripping dashes and spaces) so a permit written “301-45-678” and an assessor record written “30145678” resolve to the same parcel — which is how a permit gets fused with its owner’s mailing address and the property’s last sale.
Related questions
- How do I find a property’s APN?
- Look it up on the county assessor’s website by address, check a recent property-tax statement or deed, or search the address on PlumbIntel — the APN appears on the property record.
- Is an APN the same as an address?
- No. The APN is a permanent parcel ID; a parcel can have multiple addresses and addresses can change, but the APN stays the same.
- What does the Maricopa County APN format mean?
- It’s 8 digits as book-page-parcel (###-##-###): map book, map page, then the parcel number on that page.
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