DETROIT — In filing its 2009 annual report on Wednesday, General Motors completed an important step toward becoming a public company again.

The report uses fresh-start accounting, essentially wiping GM’s books clean after its bankruptcy reorganization last summer and starting over.

The work took more than 1,000 man years to complete, according to GM. “This was a major undertaking … and our first step in preparing to take GM public,” GM Chief Accounting Officer Nick Cyprus said.

GM’s bankruptcy reorganization reduced liabilities by $83 billion. Under the new accounting, GM’s property, plan and equipment were valued at $19 billion — an $18 billion reduction.

GM has paid back $2.8 billion in loans to the U.S. Treasury and Canadian governments. The outstanding balances — $5.6 billion — will be repaid by June at the latest, GM reiterated.

But U.S. taxpayers’ real payoff for the nearly $50 billion pumped into the automaker will come when GM goes public again.

“I know there’s a huge interest in when that might actually be, and the best I can indicate is: when the markets and the company are ready,” Chris Liddell, GM chief financial officer, told analysts and reporters.

Based on GM’s May 31 turnaround plan, GM financial advisers estimated in a presentation to GM’s board that the new GM would lose $1.3 billion before taxes this year and make $3 billion before taxes in 2011.

Those projections say that GM will make $1.6 billion in 2010 on an operating basis, also known as earnings before interest and taxes.

From July 10 to Dec. 31, 2009, GM lost $4.3 billion on $5.7 billion in revenue.

A big chunk of those losses include $2.6 billion spent on the UAW’s retiree health care trust and $1.3 billion from foreign currencies being measured differently.

“Despite the results that you’ve seen for the fourth quarter, I believe we have a chance of achieving profitability this year at least at the operating level,” Liddell said. “This is a long way from the results that we’re showing for last year but reflects the progress that we intend to make in the market place and on our cost structure.”

GM said it ended 2009 with $36.2 billion in cash and marketable securities, dramatically better than at the end of 2008, when GM had just $14.2 billion on hand, thanks to U.S. government loans.

Last November, GM gave third-quarter results under a different accounting system. At the time, it said it lost $1.2 billion in the quarter after emerging from bankruptcy and ended the period with $42.6 billion in cash.