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Reassessment methodology

While assessing units can conduct a reassessment by individually appraising all parcels for the same roll year (a full reappraisal), the definition in RPTL §102 (12a) does not necessarily mean that every property must be individually appraised to be considered a reassessment.  Assessing units can also conduct a reassessment by trending all parcels or through a combination of reappraisal and trending.  Either of these approaches is considered a non-reappraisal reassessment. 

In determining which approach is the most appropriate, each assessing unit must consider the length of time since its last reappraisal and whether sufficient market data is available to demonstrate uniformity within the groups identified for analysis.  Trending is not recommended for use in groups for which there are insufficient market data to demonstrate uniformity.  Whether or not uniformity can be demonstrated, it should be recognized that the development and on-site review of individual values (reappraisal) will yield more accurate and equitable assessments because all properties in a group do not appreciate or depreciate at the same rate. 

Regardless, all reassessments involve a systematic analysis in which all assessments are compared to the current market and adjusted as necessary to a desired LOA to achieve equity.  Systematic analysis is the process of reassessment that includes the gathering of data and market information, the grouping of this data for further study, the application of accepted analytical techniques both diagnostic and prescriptive, and the subsequent validation of results before values are implemented on a tentative assessment roll.

Statistical analysis is used to ultimately draw conclusions about the level and uniformity of the assessments from the previous year's assessment roll as compared to current market conditions.  Based on the indicators of level and uniformity produced by this ratio analysis by group, the assessor determines which assessments on the upcoming roll will be changed and how:

  • If the analysis indicates that uniformity in a group is acceptable to good and that assessments are already at the desired level, no change may be necessary (individual parcels within such a group may still require assessment changes, at a minimum, for new construction or demolition)
  • If the analysis indicates that there is acceptable to good uniformity in a group, but the assessments are not at the desired level, assessments can be trended to achieve the desired LOA
    • Trending refers to the application of an arithmetic factor to the assessments of a group of properties to reflect increasing or decreasing property values over a period of time. A 5% trend would indicate that property values have increased 5%
  • If the analysis indicates that there is a lack of uniformity in a group - or there is not enough data to draw that conclusion - a reappraisal must be conducted regardless of whether assessments are at the desired level
    • Reappraisal means developing and reviewing a new determination of market value for each parcel, based upon current data, by the appropriate use of one or more of the three accepted approaches to value (cost, market, or income)