The income expectations are determined first, then the mill rate is established based on income expectations. The assessment values determine the proportional share each property pays, but they do not affect the total amount. The city doesn’t collect more just because property values are higher. If a city has constant income needs then the tax rate will go down if assessments come in higher.

But Toronto is not having its income needs met, all while having some of the lowest property taxes in the province, both in tax rate and in property receipt amounts. The solution seems pretty obvious.