Stanford University published a working paper earlier this year that revealed a glaring racial disparity in audits of Black taxpayers. The study prompted some lawmakers to urge the agency to conduct an internal investigation into how it determines which taxpayers to audit.

On Monday (May 15), the IRS confirmed the suspicion that it has a racially biased audit selection system.

“While there is a need for further research, our initial findings support the conclusion that Black taxpayers may be audited at higher rates than would be expected given their share of the population,” IRS Commissioner Daniel Werfel wrote to the U.S. Senate.

Rep. Bill Pascrell, a New Jersey Democrat on the House Way and Means Committee, said he and his colleagues raised concerns in March about the over-audits of Black taxpayers. The committee oversees the federal tax system.

“IRS is making strides but extra audits of Black Americans is disgraceful and must end,” Pascrell tweeted.

The Stanford study estimated that the IRS audits Black taxpayers at three to five times the rate of non-Black taxpayers. Since the agency doesn’t collect data about taxpayer race, it appears the disparity stems from the agency targeting people who claim the Earned Income Tax Credit (EITC), a benefit for low-wage workers that has a high rate of mistakes.

“We are deeply concerned by these findings and committed to doing the work to understand and address any disparate impact of the actions we take,” Werfel wrote, adding that the agency is “dedicating resources” to figure out why its automated audit selection produces a disparity.

CBS News reports that the agency intends to use some of the $80 billion it received through the Inflation Reduction Act to understand the problem, which the Stanford study suggested that it stemmed from the agency’s flawed artificial intelligence algorithm.

Werfel said his office will update the lawmakers on a regular basis on its progress toward fixing the problem.