Toshiba's accounting probe

(Reuters) - Toshiba Corp on Monday announced a summary of an independent investigation into accounting irregularities.

People familiar with the matter said it could result in up to 400 billion yen ($3.2 billion) in charges and the resignation of Chief Executive Hisao Tanaka.

Following are key moments in the saga since Toshiba first announced the accounting probe in April.

April 3 - Toshiba says probing possible improper accounting, may have under-reported costs of infrastructure projects in the business year through March 2014. Says looking into whether it adequately spread costs of multi-year projects in its accounts.

May 8 - Expands investigation, plans to set up third-party committee. Cancels dividend payment, withdraws earnings outlook.

May 13 - Says likely to mark down operating profit for the three years through March 2014 by at least 50 billion yen.

May 15 - Launches independent committee headed by a former prosecutor to broaden probe.

May 22 - Extends probe to three more business units.

May 26 - Firm likely to seek extension to annual securities filing deadline to avoid being placed under supervision by the Tokyo stock exchange, sources say.

May 27 - Considers special dividend to compensate investors after skipping year-end payment due to probe, sources say.

May 29 - Toshiba says accounting probe to end mid-July, gained approval to release annual report by August-end, first-quarter results by Sept. 14 - one month later than usual bourse deadline.

June 12 - Says internal investigation found further instances of improper accounting amounting to 3.6 billion yen. Says that investigation, running parallel to third-party probe, found 12 instances of irregularities, including not making provisions for a canceled contract, postponing recording of expenses, underestimating material costs.

June 25 - CEO says may appoint more outside board members to improve accounts oversight.

July 8 - Firm talks with banks about up to $4.9 billion credit line to secure funding in case probe hurts creditworthiness, sources say.

July 9 - Considers selling assets including a stake in Westinghouse Electric, sources say.

Independent investigation looks into roles top management played in accounting practices, sources say.

July 15 - Firm expects to book charges of 300 billion yen to 400 billion yen related to improper accounting, sources say. Charges include six years of overstated profit and various writedowns, they say.

CEO, other board members including Vice Chairman Norio Sasaki to step down in September to take responsibility, sources say.

July 16 - Independent panel finds top executives involved in improper accounting practices, source says.

July 17 - Toshiba says third-party committee to submit report to the firm on July 20. Says to release entire report, hold news conference at 5 p.m. (0800 GMT) on July 21.

July 20 - Independent panel concludes Toshiba overstated its operating profit by 151.8 billion yen over several years.

The report says Tanaka and his predecessor, Vice Chairman Norio Sasaki, were aware of the overstatements of profits and delays in reporting losses in a corporate culture that “avoided going against superiors’ wishes”.

Compiled by Miyoung Kim; Editing by Christopher Cushing