The overstatement was roughly triple Toshiba's initial estimate. Sources have said Tanaka and Sasaki would resign in the coming months and most of the board would be replaced to take responsibility for the shortcomings.
The report says much of the improper accounting, stretching back to fiscal 2008, was intentional and would have been difficult for auditors to catch.
The report said Tanaka and Sasaki, who were also successive presidents, had set operating profit targets that the heads of divisions were required to meet, applying pressure by hinting at withdrawing from areas that underperformed.
"Within Toshiba, there was a corporate culture in which one could not go against the wishes of superiors," the report said.
"Therefore, when top management presented 'challenges', division presidents, line managers and employees below them continually carried out inappropriate accounting practices to meet targets in line with the wishes of their superiors."
The investigation comes as Japan's Prime Minister Shinzo Abe is trying to improve the country's corporate governance in order to attract more foreign investors.
Read MoreToshiba faces $3B charges over accounting scandal: Sources
This is the country's biggest business scandal since camera and medical equipment maker Olympus Corp's 13-year cover-up of $1.7 billion in losses blew up in late 2011.
The scandal also shakes a stalwart of Japanese industry. Toshiba remains Japan's 10th-biggest company by assets and market value despite its stock price falling 26 percent since the scandal surfaced in early April.
Toshiba has not been able to close its books for the latest year because of the probe, which also forced the company to cancel its annual dividend.
Tanaka and Sasaki will likely step down and more than half of the board will be replaced at a shareholders' meeting in September, sources said.
The committee is to hold a news conference at 7 p.m. (1000 GMT) on Tuesday, according to the filing.