The Census Bureau failed key tests related to hiring and recruiting, according to a new audit, putting the agency in a precarious position as it prepares to bring on half a million employees for its 2020 decennial count.

The failures were so severe they “present a risk to the successful completion of the 2020 Census program,” according to the Commerce Department’s inspector general, which issued an alert to management to notify the agency of its concerns. The tests involved two systems—Decennial Applicant Personnel and Payroll and the Census Hiring and Employment Check—that support the bureau’s selection, hiring, background checks management and other personnel activities.

Census conducted the assessment as part of its Performance and Scalability Test earlier this year, which aims to ensure the bureau’s systems are functioning properly. The personnel and payroll system, however, failed five out of six test scenarios. The hiring and employment system failed all five of its tests. The systems were overwhelmed, the IG found, and were not ready to meet the demands that will be placed on them early next year as Census will be forced to process more than 2 million applications.

The bureau must be able to automate certain administrative functions to complete its count next year, such as clearing, hiring, processing and paying staff. Agency management said it would conduct additional testing this month once it receives a software update from its vendor, but the IG warned that would leave little time to address any lingering concerns. The auditor also warned that Census “does not have a documented contingency plan in place” if the systems continue to fail, noting management’s suggestion it could simply limit the number of concurrent users would lead to significant delays and cost overruns.

Michael Cook, a Census spokesman, disputed the IG’s alert, saying it relied upon outdated information and the findings were no longer relevant.

“We understand the critical nature of our hiring and payroll systems and are extremely confident that both systems will function as intended during peak 2020 Census operations,” Cook said. He noted the systems in question have remained in place since the 2010 enumeration, when they were deployed successfully.

The bureau has already reached its load testing targets for its anticipated peak operations, Cook said.

Census last month completed the first major step for next year’s count, carrying out its address canvassing. The agency has already received 750,000 applications and will require fewer employees than it did 10 years ago, when it fielded 3.9 million applications and hired 628,000 temporary workers. For the first time ever, Census is directing households to fill out their forms online. Still, a recent Government Accountability Office report found “external factors beyond the bureau’s control,” such as the low unemployment rate, could make it harder to recruit. Census is also facing longer-than-expected wait times for background checks, GAO said.