What is tax increment financing (TIF)? 

"Tax Increment Financing (TIF) is a method of re-allocating property tax revenues which are produced as a result of an increase in taxable valuation above a "base valuation" figure within a tax increment area. Until the tax increment debt within an area has been repaid, tax revenues produced by property tax levies imposed on the increased taxable valuation by a city, county, school district, area school, or any other taxing jurisdiction are all allocated back to the city or county which has established the tax increment area, and must be spent by that jurisdiction for projects within that area" (Josten, Dorsey, and Whitney; Des Moines). 

"Tax increment financing areas are created as a means to maximize property tax dollars within particular areas, in order to pay the cost pf public improvement projects (streets, water, sewer, etc.) or to make direct economic development grants or loans to private enterprise as an incentive to locate within the tax increment financing area. The funds must be spent within the area and may not be used by cities or  counties to supplement their general obligations" (Josten, Dorsey, and Whitney; Des Moines) .

Where can I read about TIF in the Code of Iowa?