Internal Revenue Service chief Frank Bisignano may have lied to Congress about staffing issues as the tax agency races to hire after making deep personnel cuts at the beginning of the Trump administration, a group of Senate Democrats led by Sen. Elizabeth Warren alleged in a letter sent late Wednesday and shared exclusively with CNBC.

Bisignano, who is also the Social Security Administration commissioner, testified before Congress in March that he “feel[s] good about the number of employees [he] has right now” at the IRS. He also denied that his agency was understaffed before the Senate Finance Committee in April.

Warren, D-Mass., and the other Democrats, however, said in the letter that Bisignano’s testimony doesn’t align with recent news reports that the IRS is aggressively surging hiring. They also point out that the agency’s own inspector general cited staffing shortages as a major concern for the agency, while pointing to an internal memo reported by NOTUS that requested expedited hiring authority due to “ongoing staffing shortages [that] put the 2026 Filing Season at risk.”

“New reporting suggests that the IRS understood the need for more agency staff, despite your public assertions to the contrary,” the Democrats wrote in the letter sent. “This discrepancy requires an explanation. Under federal law, persons who ‘knowingly and willfully … make any materially false, fictitious, or fraudulent statement or representation’ to Congress may be subject to penalties.'”

More than a dozen Democrats signed onto the letter, including Senate Finance ranking member Ron Wyden, D-Ore. Sens. Sheldon Whitehouse, D-R.I., Peter Welch, D-Vt., and Raphael Warnock, D-Ga., were also among the letter’s signatories.

Knowingly lying to or misleading Congress could be a crime.

The IRS did not immediately respond to a request for comment.

The letter is the latest headache for Bisignano, who was forced to play defense earlier this week after The Wall Street Journal reported he had spied on his former colleagues at JPMorgan Chase. The IRS chief has denied the report, which said he had used his security authority to snoop on his colleagues’ communications and access sensitive information.

In his current role, Bisignano sits atop agencies with swaths of confidential information about nearly every American.

It also comes in the wake of last year’s massive federal government layoffs led by Elon Musk‘s Department of Government Efficiency. The IRS alone hemorrhaged more than 31,000 employees as of January 2026, according to a report from the agency’s inspector general, a gap that Bisignano has said is being filled by the adoption of new technologies.

The IRS IG said in the June report that staffing had contributed to delays in the agency’s work.

“We also know that many departing employees were experienced workers with institutional knowledge and technical expertise that cannot easily be replaced,” the IG said in the report. “In our 2026 Filing Season memorandum to the IRS Commissioner, we warned that the IRS faces elevated operational risks for the season due to staffing shortages, delayed hiring, and significant backlogs. For example, key inventories waiting to be processed (such as amended tax returns and taxpayer correspondence) have significantly increased.”

Warren and her colleagues demanded that Bisignano clarify whether the reports that the IRS was seeking special hiring authority are accurate and whether he was aware of the internal memo asking for the authority and read it before his testimony to Congress.

They also asked him to clarify his basis for telling Congress that there “was ‘no staffing shortage’ at the IRS while at the same time seeking hiring authority due to a ‘critical hiring need.”