Percent Change of the Income Tax Rate in Illinois

In July 2017 the Illinois State Legislature raised the income tax rate from 3.75% to 4.95%.  This change can be described two ways.  “The tax rate increased by 1.2 percentage points.”  or  “The tax rate increased 32%.”

Percent change = change/original = 1.2/3.75 = .32 = 32%

Percent change is the primary way that we (and the media) describe change. When the data itself is a percent, it can be a bit confusing. 

See also:

• https://www.slideshare.net/mobile/DrOlsen314/more-percentapplications24
• http://faculty.wiu.edu/JR-Olsen/wiu/BootCamp/24-percent-tweets.html