A congressional committee looking into wrongdoing within the Washington Commanders N.F.L. franchise referred to the Federal Trade Commission allegations of potentially unlawful financial practices by top executives.

According to a 20-page letter sent to the F.T.C. on Tuesday, a former longtime executive in the ticketing department accused the team of keeping “two sets of books” in order to conceal hundreds of thousands of dollars of revenue that was supposed to be shared with all 32 N.F.L. franchises. The executive said the Washington team also took intentional steps to keep as much as $5 million in refundable security deposits from customers, including an account that appears to be registered under N.F.L. Commissioner Roger Goodell’s name.

The allegations of potential fraud were gathered as part of the investigation by the House Committee on Oversight and Reform into accusations of sexual harassment of women in the team’s front office dating back as far as 15 years. The Washington Post first reported on the committee’s letter to the F.T.C.

Ashley Whitlock, a Commanders spokeswoman, said the team had no comment. She referred to the team’s statement on March 31.

“The team categorically denies any suggestion of financial impropriety of any kind at any time,” the Commanders said then. “We adhere to strict internal processes that are consistent with industry and accounting standards, are audited annually by a globally respected independent auditing firm, and are also subject to regular audits by the N.F.L. We continue to cooperate fully with the Committee’s work.”

If true, the allegations would raise serious concerns inside the N.F.L. because 34 percent of ticket revenue from home games is supposed to be shared with the 31 other teams and the players. If the Washington franchise withheld revenue from the other team owners for a period of time, it would raise questions about the quality of the audits done by the league, the N.F.L. Players Association and the team’s audits of its own books.

The scheme, if proven, could also increase the pressure on the N.F.L. to penalize Daniel Snyder, the team’s owner, who has faced calls from critics to sell the franchise.

High-level executives with other teams did not dismiss the possibility that such a scheme could take place, though they said it would be challenging to escape detection, especially as more teams use digital tickets that are difficult to manipulate.

The executives noted that each team creates a ticket manifest at the beginning of each season that lists tickets for sale that year, and the N.F.L. tracks each ticket sold or not sold electronically. That record is then matched against the manifest to determine how much revenue the team is supposed to share with other teams.

The congressional committee’s letter details the tactics allegedly used by Washington, based largely on its interview in March with Jason Friedman, who worked for the team for 24 years and last served as a vice president of sales and customer service, as well as supporting documentation he submitted. Friedman was fired in October 2020 for poor performance and inappropriate behavior, according to the team. He testified to the committee about a practice he said some team executives called “juicing,” in which money was intentionally misallocated in the team’s accounting system and used for other purposes.

Friedman provided the committee with two email exchanges, from April 2013 and May 2014, in which he said he conferred with Washington team executives about moving N.F.L. ticket revenue into other categories that would not be subject to the league’s revenue-sharing program, such as licensing fees for college games or concerts hosted at the team’s stadium in Maryland. In testimony cited in the letter, Friedman said that team executives kept one set of books with the altered numbers submitted to the N.F.L. and a second set with the accurate accounting that was shown to Snyder.

Friedman, who said he oversaw the processing of security deposits, also told the committee that after Snyder bought the team in 1999, the team intentionally made it difficult for ticket holders to recoup their refundable security deposits. While the team stopped collecting deposits for most seat leases about a year after Snyder became the owner, Friedman shared with the committee information exported from the team’s electronic database to support his claim that, as of July 2016, the team had retained security deposits for about 2,000 accounts totaling around $5 million.

The letter includes screenshots of the spreadsheet Friedman provided to the committee cataloging these ticket holder accounts, including one under Goodell’s name with an unreturned security deposit of about $1,000. The committee wrote that the deposit appeared to have been collected before Goodell became commissioner in 2006 and that it had not determined when it was paid or whether the amount had since been refunded.

Friedman further testified that his boss would direct him to convert unclaimed security deposits into “juice” at Snyder’s behest, particularly when the team’s sales were sagging. Snyder gave directions to stop this practice around 2017, Friedman told the committee.

There was no other evidence presented in the letter that directly linked the scheme to Snyder.

In a statement, a spokesman for Republicans on the Oversight Committee pushed back on the allegations in the letter. The Democrats on the committee, he said, were “attacking a private company using the claims of a disgruntled ex-employee who had limited access to the team’s finances, was fired for violating team policies, and has his own history of creating a toxic workplace environment.”

Brian McCarthy, a spokesman for N.F.L., said the league continues to cooperate with the committee and has provided more than 210,000 pages of documents. The league appointed Mary Jo White, a former federal prosecutor, to “review the serious matters raised by the committee” including allegations of sexual harassment against Snyder that were raised in a congressional hearing in February.

Those allegations were made eight months after the league fined the Washington team $10 million and forced Snyder away from the team for several months after a separate investigation found evidence of harassment against women in the team’s front office.