The OU Student Government Association and Econ Club hosted a panel discussion on TIFs.
These are my slides.  I have added notes below each one.

NOTE: The "But For" condition is more difficult to establish for Greenfields.

Note: This is an example for the University North Park TIF in Norman, OK.  

Note: Above is a classic picture of how TIF works.  Note the targeted area is declining or stagnating (satisfies the But For condition).  The tax revenues are frozen at the base level. Growth in tax revenues in the district are re-invested in the district.  Borrowing can be done and paid back with the increment growth. At the end, the City gets the who value of the base + the increment.

Note: There are a lot of players. Keep in mind that interests may conflict. Lawyers may work for developer or the gov. Consultants may get paid to manage the contracts. Schools give up (or receive a bonus) from freezing the base.

The growth in the increment may not be an accurate measure of the impact of the investment.  The extra growth resulting from the investment is the difference between actual increment growth and the alternative “No-TIF” scenario.  If nothing would have happened at all (think brownfield or high poverty neighborhood) then the increment might be a good measure of TIF impact in the district.  More than likely (especially for greenfield development) some growth would have happened without the TIF. 

The increment may be split between the TIF district and the taxing jurisdiction. The impact on the budget would depend on the difference between the City’s take in the TIF vs. the NO-TIF scenario. (We don’t observe the no-tif scenario).

Note: It isn’t enough to look at what happens just inside the TIF b/c the TIF project can detract from or enhance growth in the rest of the community.  If the TIF does not pass the but for test, then the TIF “wasted” $.  The TIF might also grow at the expense of the rest of the community

Note: One type of cannibalization is where stores or private investment relocates within the TIF. This may be new to the community or it may be relocations within the community. Relocations within the community do not add a net benefit. (Move the cheese )

Note: Another type of cannibalization is where shopping activity shifts to the TIF district and away from the non-TIF district.  This can impact the City budget b/c the City only gets a share of the TIF increment growth. The stores outside the TIF suffer from the TIF competition. (spread the cheese)

Note: A good first approximation of overall impacts within and outside the TIF is to look at the total sales tax base (or advalorem if property taxes are involved).  In the above graph we do not observe a bump in total sales tax activity after the University North Park TIF.  Norman's trend is similar to that of other cities in the region, Edmond and Moore.  This is not a clean analysis because Edmond and Moore use TIFs also. 

Note: TIFs are a tool that can be used to enhance growth and development if used for the right sort of projects and designed properly.  TIFs can impact city budgeting in important ways.
These deals need very careful analysis from objective parties vs. stakeholders who have a hand in the pot.