The Effects of Taxmageddon on Illinois
Created on June 14, 2012
Understanding the Data in the State & Congressional Tables
The data used to create these estimates are based on the most recent available IRS and Congressional District information. Two factors are important for the reader to keep in mind:
1. 2010 Congressional District Lines. The Congressional District data are drawn from the districts as they existed in 2010. While the general shape of the new district lines is known, not enough detail down to the zip code level is available for CDA to produce tax estimates based on new district lines.
2. Tax Data Based on IRS Numbers. CDA used IRS estimates and data in the following manner:
AGI Estimates for 2013 are based on the historical growth of adjusted gross income that occurred between 2006 and 2010, as well as IRS estimates of tax returns for 2013. Note that the average is based on “per tax return,” not per person; thus, if a husband and wife file jointly they will see the identified tax increase as a family, not per individual.
Total National Tax Increase is based on estimates from the Office of Management and Budget and Joint Committee on Taxation as detailed in research by Heritage analyst Curtis Dubay.
Congressional District Tax Increases – Using 2006 and 2008 IRS data, CDA used personal income tax data at the zip code level to calculate tax increases in each district.
State Tax Increases were determined by summing or averaging across the congressional districts.
For a more in-depth explanation of the methodology used, please go to http://www.heritage.org/issues/taxes/taxmageddon.
 Adrian Dungan and Michael Parisi, “Individual Income Tax Returns, Preliminary Data, 2010,” Internal Revenue Service, Statistics of Income Bulletin, Winter 2012, Figure A, p. 6; information about the zip code–based IRS tax data can be found at http://www.irs.gov/taxstats/indtaxstats/article/0,,id=96947,00.html .(last accessed June 4, 2012).