Thousands of tax delinquents, including one who owes the IRS $2 million, have sensitive security clearances, posing a risk that has gone undetected by federal agencies, congressional investigators will report this Thursday.

According to a General Accounting Office report, 8,400 U.S. officials and contractors with access to sensitive government secrets have racked up $85 million in delinquent tax debts, NBC News reports.

The report is the latest example of what members of Congress and investigators say are glaring weaknesses in the government’s system of vetting those receiving security clearances, the article says.

The GAO study did not examine members of the U.S. military or employees of U.S. intelligence agencies with clearances. It focused on 240,000 officials and contractors with clearances elsewhere in the government, such as Homeland Security, State and Energy departments.

The report states that an official or contractor with tax debts is “at risk of having to engage in illegal acts to generate funds” and could therefore put national security secrets at risk. The current federal background check system does not check federal tax databases before granting clearances, instead relying on “self-reporting” of debts and checking of credit reports – which do not disclose tax debts unless liens have been filed.