The earned income tax credit, or EITC, is a program designed to help boost low-income workers out of poverty. In response to pressure from congressional Republicans to root out incorrect payments of the credit, the IRS audits EITC recipients at higher rates than all but the richest Americans.

Kim M. Bloomquist, who served as a senior economist with the IRS’ research division for two decades, decided to map the distribution of audits to illustrate the dramatic regional effects of the agency’s emphasis on EITC recipients. In a study first published in Tax Notes, he found that because more than a third of all audits are of EITC recipients, the number of audits in each county is largely a reflection of how many taxpayers there claimed the credit.

The included data covers the total number of income tax filings and the estimated number of audits per county, for the combined tax years 2012-15.

The data is also available, along with our analysis scripts, on Github.