Why would they pay more tax than they are required to? Why would they not argue that their properties are overvalued if they believe them to be? Seems to me th

Why would they pay more tax than they are required to? Why would they not argue that their properties are overvalued if they believe them to be? Seems to me that it might be a good idea to issue retroactive tax bills (or refunds!) based on the actual price when a property finally does sell. So if they're honestly right that these properties are worth less, then they'll see for less someday, and they don't need to worry about a retroactive bill. OTOH, if they're wrong — there'd be principal & interest to pay. This might even help keep property prices low, which is (I think) generally a good thing, since there are so many forces acting to keep them high. I dunno — maybe someone can point out the flaws.