Understanding the Data: Assessed Property Values

Here at LandLink we believe that decisions are made better when people have access to the right data and analysis. That's why it's critical for us to find the right sources of information on our cities. Just as important, however, is making sure our clients and the residents they serve understand the numbers that surround their communities. To help everyone make sense of the changes taking place in their cities, we decided to publish brief guides to urban development data, including its key features, pros and cons, and how to access the source files directly.

Overview of Assessed Property Values

The first topic in our series on data will be assessed property values. These figures are part of every city's public property registry, a giant database of every plot of land within the municipal or county boundaries. The registry contains information on where certain plots of land are, what they are used for, who owns them, and how much they are worth. It's important to note that the assessed value of a property is different from the sale value, or what a plot is worth on the real estate market. Governments assess property value for the purpose of levying taxes; these estimated values are updated regularly to ensure fair and accurate taxation. The assessed value often takes cues from the sale value, but can also differ drastically due to various local property tax regulations such as tax freezes. Despite these differences, assessed values are often more useful for answering urban development questions, which is why we use them in our own work.

Advantages of Assessed Property Value Data:

  • Completeness - Every city or county in the United States has a public tax assessors office that manages and updates the property registry. This means that every property in the area is accounted for and valued regularly, creating years of data that can be used for measuring changes over time. Assessed values are also accompanied by tax classification data (residential, commercial, exempt, etc), geographic data, and key variables such as lot acreage.
  • Regularity - While sales values can differ depending on how property owners or real estate agents value a plot of land, assessed values are determined using a standardized framework. This ensures that data is comparable citywide and over multiple years.
  • Accessibility - Sales values are also more difficult to acquire, relying on third party aggregators like Zillow to compile data using proprietary algorithms. Assessed values, meanwhile, are available free of charge from the tax assessor's office and are already packaged in simple CSV or SHP file formats.

Disadvantages of Assessed Property Value Data

  • Infrequent Assessments - Tax assessors must maintain huge registries on thousands of properties, meaning they cannot update the value of every property each year through traditional techniques. This can cause assessed values to lag behind sales values by one to four years, complicating any analysis that looks at change over time.
  • Special Tax Considerations - Since assessed values are used primarily for calculating property taxes, they are often adjusted to account for special considerations like tax exemptions and freezes, which artificially lower a property's assessed value. These techniques are important for local governments and development but if not accounted for can skew value data.

Accessing Assessed Property Value Data

Acquiring data files on the assessed value of properties in an area is usually quite easy, but differs for each county. The best source for property data is often the local tax assessor, who can usually be found through public websites. Sometimes data files are available for download directly from the assessor's website, but if not all it takes is a simple request for information by email. The request should specify the geographic boundaries of the data (countywide, city limits, downtown, etc), years of interest, and any other special variables (such as number of bedrooms or bathrooms for residential properties). When in doubt it's best to ask the local assessor what data is available or describe the reason for accessing the data. Our team at LandLink has received a great deal of guidance from the tax assessor's office for Macon-Bibb County and we're sure many other offices are happy to help. 

If you have any questions about using assessed property value data in your work, please don't hesitate to contact us at landlinksystems@gmail.com or leave a comment below!