Using GIS to Compare Regional Sales Tax

​The Illinois Department of Revenue provides municipalities with sales tax data they can use to compare tax rates by municipality, county, or special commercial area.  To better understand how the Village of Woodridge’s general merchandise and telecommunications sales taxes compare to surrounding communities, the village’s Finance department asked the village’s Geographic Information System (GIS) department to create a custom data layers that shows the regional distributions of these taxes.  These custom layers were able to display this information visually in the village’s interactive mapping application, MapOffice™, in a readily available way, as opposed to making comparisons line by line using a spreadsheet.

These custom layers were created by dividing the tax information up by municipality and special commercial area boundaries based the county in which they exist, which in turn defines the sales tax for that community.  Once these boundaries had been created, they were symbolized based on their total sales tax rate. To visualize the makeup of each areas total sales tax rate, a Microsoft Excel Macro was used to generate a pie chart for each area.  Each of these charts was then embedded in the GIS attribute information for each area, so, when the user clicks on an area in MapOffice™, the chart is displayed.  By embedding chart-based analytics within a custom map layer, users can easily make visual comparisons of sales tax between communities, helping the village Finance department staff to be more efficient and productive with the time they spend working on requests related to this information.