Yeah, I think that's fair, and probably worth taking a hard look at in future TIF studies. I don't think either way is wrong, just diff interpretations of how TIF works.

I saw Prof. Weber mentioned the differences in a paper back in 2007, if you're interested (p10): www.cdfa.net/cdfa/cdfaweb...

(I don't have an official answer bc the Clerk's Office handles TIF distribution.)

I think in the past the Clerk was limited by the old mainframe. The new way is how many collar counties do the calculation (see Lake, for example), and IMO it's more transparent.

www.lakecountyil.gov/268/Tax-Exte...

It's one reason why this year the tax amount going to south suburban TIFs increased by 19%, even though it's not a reassessment year:

This means individual properties in a TIF will have different distribution percentages depending on how much each property's value increased.

The main difference is that now TIFs with a lot of properties losing value will collect more money, because any property gaining value will add increment.

I've seen some great articles on our report, including pieces in the Tribune (featuring web maps!), the Sun-Times, and Crain's. Give them a read!