If your property experienced the same increase in value as the average, its new value would be multiplied by the new mill rate. If the City’s budget didn’t increase, and your assessment increased by the average, you do not end up paying more tax because it evens out.
But what if your property value increased by less than the average? In this scenario, an assessment increase that is less than average would actually result in your municipal taxes going down. And if your property value went up by more than the average, your municipal taxes (or your "share" of the costs) would increase.
Of course, most municipalities are facing the challenge of rising costs, both conventional inflation and cost pressures from such issues as downloading, increased regulation and climate change. But the principles are the same if your city institutes a 3% tax increase; if your property value increases by the same as the average, then you’ll face the 3% budget increase. Most properties, though, will face assessment increases either higher or lower than the average (and a few will see decreases).