Assessed Values

Data Element


The most recent property values as established by the Tax Assessor. This can often consist of an assessed value used in determining property taxes and a separate market valuation.

ATTOM ID 145695081
Assessor Year 2022
Assessed Value $84,762
Improvement Value $59,912
Land Value $24,850
Market Value Year 2022
Market Value $242,177
Market Improvement Value $171,177
Market Land Value $71,000


Mortgage: As part of risk mitigation, mortgage companies have a need to closely monitor property prices after mortgages and other loans have been provide

Property Analysis: Any analysis based upon property values can 

Note: Market values sourced from County Tax Assessors are usually considered to be only a rough approximation of a property's value. For applications requiring a more accurate estimate of a property's value AVM models will be used.


Many, but not all, counties make assessed values available as public record data that can be collected in the same way as other data published by County Tax Assessor. ATTOM Collects this data and matches it against its property databases, assigning an ATTOM ID which allows our customers to cross-reference this data with other property data. Counties update assessed values at most once per year, with some counties only updating data every 2-3 years.


The following tables can be used to access Census Block information. When delivering solutions to customers, some or all of the information found in these tables may be consolidated into one or more views.


For each property, a history of the details about the latest assessment of the property's value and the year in which that assessment was made.

Rows: 11 million
Columns: 4
Family: Boundary


Cross-reference table providing the identity of commonly used geographic boundaries matched to a property. The boundaries are: -

  • Census Block
  • Census Block Group
  • Census Tract
  • Census FIPS Place
  • CBSA
  • Minor Civil Division
  • MSA

Rows: 16 million
Columns: 15
Family: Property

Dimension Tables

DimBlock: Details for each of the ~11 million Census Blocks assigned to properties by the US Census Bureau

DimGeographType: The complete list of geography types used as boundaries as well as the dimension table used to provide details about each boundary

Understanding the Data


Because there is not a universally accepted standard for property identification (like the use of SSN to identify US citizens), properties can be difficult to identify. Alternatives such as APN or street address can change over time and they often lack a consistent way of being formatted. ATTOM addresses this by assigning a single, permanent identifier to each property in the form of a very precise number (integer).


A unique code is used to identify each class of boundary. For Census Block the GeoghraphyKey is 33


A unique number is assigned to each boundary of a specific class. For example, each Census Block has been assigned a unique by ATTOM separate from the numbers assigned by the US Census Department. Being a number, the performance of queries run against millions of records ATTOM CLoud data can be dramatically improved. The Geography Key is unique only for Census Blocks.


The GeoID is a 16-character string that uniquely identifies a boundary across all classes of boundaries. This key is used for special purposes such as locating the shape file with the coordinates of a boundary.

Block Code

The Block Code is a 15-digit number assigned by the US Census Department that uniquely identifies a Census Block

  • Block Code: 060670011011085
  • State: 06 California
  • County: 067 Sacramento
  • Tract: 001101 Tract 11.01
  • Block: 1085 Block 1085


The "name" assigned to each block is a four-digit number that is unique within a Census Tract

Product Articles (P-Articles)

All solution packs containing the Census Block data element will include the following p-articles to help you understand and use the data: -

  • Census Boundaries 101
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