# Year-over-year tax rate comparisons with no constants?

Is it possible to derive a single formula to track year-over-year changes in effective property tax rate when all values fluctuate?

My inclination is that this is not possible, but I would like to confirm.

The formula is essentially $\text{Assessment} - \text{Exemption} * \text{Tax Rate}$.

The problems seem to stem from the following:

• The $\text{Assessment}$ and $\text{Exemption}$ amounts vary from year to year
• There are multiple rates, only some of which the exemptions apply to

How do I isolate the dollar value impact attributed to changes in the rate if the taxable value does not remain constant from year to year?

The general theme here is that fluctuations in all rates are not created equal. A increase in one rate may have a more significant impact than another. It all depends on the relationship between the assessed value and taxable value (assessed less the exempt portion).

The idea would be to normalize the impact so that a meaningful metric can be applied across the board.

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