So I just got my proposed property tax valuation for 2023 in the mail. My valuation went up about 21% and the taxable valuation went up over 24%! We haven't done any changes to the house. I'm wondering if it will do any good to talk to the assessor about this...
Every state has its own methodology for calculating taxable value. I see that you live in Minnesota, so you can Google Minnesota taxable valuation to locate several sites that explain the methodology, or you can call your local assessor or other resources. From one of the online sites, it appears that Minnesota has a progressive valuation system, wherein a portion of the valuation is excluded up to certain property valuations, dropping off as the property value rises. You apparently have a property whose value exceeds the top level of the progressive scale.
The dramatic increase in real estate values would cause your estimated valuation to increase. Sales for the region show that values have increased by 21%, so that has been applied across the board and accordingly the estimated valuation was increased by 21%. BUT, your property is valued highly enough that the increase is above the top value of the progressive scale, hence your taxable valuation went up by more than the 21%, ie by 24%.
If your neighborhood hasn't increased in value as much as the overall average increase, then checking sales in the neighborhood, and/or seeking the assistance of an appraiser to establish a valuation for your locale in lieu of the average increase, could be to your benefit--the assessor isn't supposed to increase your valuation in excess of the actual increase. And that COULD be less than the average. You probably have a good sense of whether that is the case, ie homes for sale in your neighborhood take longer to sell, sellers have had to lower their asking price, etc. If that's NOT the case, ie rapid sales at prices well above the assessed valuation, then your chances of a successful appeal are probably not good.
There is always an appeal process for valuations, via a board/commission of appointed citizens. Your local assessor can assist you with the proper forms and documentation to demonstrate that the average valuation increase doesn't apply to your property. In some locales, the appeal board may routinely reduce the increase, with valid documentation to support a lower value: in others, not so likely. The appeal board would very rarely increase the valuation upon appeal, perhaps aren't allowed to do so: I don't know. There have been cases in my location where reduced valuations have been appealed (2000's when the bubble burst), and higher assessed valuations requested, because owners perceived that buyers wouldn't be willing to pay more than the assessed valuation. Those usually weren't granted, the market is what it is and the assessed valuation was supposed to reflect that.