Matching APNs

The Assessor Parcel Number (APN) is used to uniquely identify a parcel of land within a specific county (or similar). The format of an APN varies from county to county.

Examples

091300 193.20-1-11.11
2984 PTN
20650530000500
57-002-2-39-08-04-1 01-000-000010
012 1 1C1*
040(01)00-003-0
02 (01 )00 /13 13A

Note: Sometimes counties will decide to change the format of their APNs resulting in existing APNs being replaced with completely new values. To get around this situation, ATTOM assigns properties a single unique ATTOM ID that never changes, is always a consistent format (a number), and is unique across all counties.

Matching APNs

The format used for an APN is also not consistent across data sources. e.g. the County Tax Assessor may format an APN as 123-456-789 whereas the County Tax Recorder in the same county may store the APN as being 123456789. To increase the chances of matching properties using APNs we recommend always stripping out special characters to produce an unformatted APN. The following code demonstrates how this can be achieved in SQL Server. It removes many of the special characters known to exist in the 3,200 counties from which ATTOM collects property data.

SELECT 
  Top 10
  Replace(Translate(pa.APNFormatted,'#:/-.(),&?_[]* ','               '),' ','') As APNUnFormatted 
From adw.PropertyAddresses pa

This may not handle all the anomalies with APNs, but it will dramatically increase the chances of matching APNs between property datasets, including your own.

Note: The PropertyAddresses view and the PropertyFeature table contain a field called APNUnFormatted. This is not populated for many properties and should not be relied upon for matching properties via APN.