What is it called when low-valued properties are over-appraised compared to high-valued properties?

The phenomenon described in the question refers to the situation where low-valued properties are assessed at higher values compared to high-valued properties. This situation is termed "Regressivity."

In a regressive assessment system, the tax burden does not proportionately reflect the true economic value of properties. Low-valued properties, often owned by individuals or families with limited financial means, may be assessed at disproportionately high values, leading to a greater relative tax burden on these owners. On the other hand, high-valued properties might be assessed too low, resulting in an inequitable distribution of property taxes.

The concept is critical in understanding how property tax assessments can lead to disparities in tax equity and highlights the importance of accurate and fair property valuation practices. Recognizing and addressing regressivity is essential for ensuring that property tax systems are equitable and just.