Parcel Number / APN Fields

Last updated: July 30, 2026

Overview

Parcel Number (APN) fields represent how counties identify property parcels and taxpayer accounts. The primary field is ParcelNumberRaw, which reflects the Assessor's Parcel Number exactly as received from the county, including dashes and formatting. Other parcel-related fields may exist depending on how a county structures parcel identifiers, including alternate parcel numbers, taxpayer account numbers, or prior parcel numbers when a change has occurred.

Details

Parcel number fields originate directly from county assessor or tax authority data and may vary by jurisdiction.

ParcelNumberRaw

  • The primary parcel identifier received from the county.

  • Preserves the original formatting, including dashes, spaces, and punctuation.

  • Intended to match the APN as displayed by the county assessor.

  • In some datasets, this may also appear as a formatted parcel number.

ParcelNumberFormatted

  • A deprecated field.

  • Maintained for legacy compatibility but should not be used for new integrations.

ParcelNumberAlternate

  • Used in counties that issue more than one parcel identifier.

  • May include location-based APNs or book/page-style parcel identifiers.

  • Represents a secondary parcel identifier.

  • Should differ from the ParcelAccountNumber.

ParcelAccountNumber

  • Typically associated with the taxpayer's account.

  • In most counties, this reflects the tax billing account rather than a unique parcel.

  • May not be unique if a taxpayer owns multiple properties.

  • In some counties, this field may match ParcelNumberRaw if the account number is the only unique parcel identifier provided or if the source data mapped the account number as the primary parcel reference.

ParcelNumberPrevious

  • Populated only when ParcelNumberRaw changes.

  • Contains the prior ParcelNumberRaw value.

  • Supports parcel renumbering history tracking.

Important Notes

Coverage

  • ParcelNumberRaw is expected on nearly all records.

  • ParcelAccountNumber is present in most tax jurisdictions but may not be unique at the parcel level.

  • ParcelNumberAlternate is populated only in counties that maintain multiple parcel identifiers.

  • ParcelNumberPrevious is populated only when a parcel has been renumbered.

  • ParcelNumberFormatted is deprecated and is not consistently populated.

Availability varies based on:

  • County data standards

  • Assessor versus tax authority reporting structures

  • Historical parcel renumbering events

Limitations

  • A shared ParcelAccountNumber across multiple records does not indicate duplicate data.

  • A populated ParcelNumberPrevious does not indicate an error; it reflects an official parcel renumbering.

  • A blank ParcelNumberAlternate does not mean data is missing, as many counties issue only one parcel identifier.

  • Formatting differences in ParcelNumberRaw, such as dashes or spaces, reflect county formatting standards and are not data inconsistencies.

  • A blank ParcelNumberFormatted field does not indicate incomplete data.

Integration Guidance

  • Use AttomID as the primary join key when linking ATTOM datasets.

  • Do not rely on ParcelAccountNumber as a unique parcel identifier.

  • Preserve the original formatting in ParcelNumberRaw when performing joins unless your downstream system requires normalization.

  • If tracking parcel continuity over time, incorporate ParcelNumberPrevious to maintain historical linkage.

  • Avoid using ParcelNumberFormatted for new development.