General Motors Co. will drive away from its U.S.-government-financed restructuring with a final gift in its trunk: a tax break that could be worth as much as $45 billion, reported The Wall Street Journal.

GM, which plans to begin promoting its relisting on the stock exchange to investors this week, wiped out billions of dollars in debt, laid off thousands of employees and jettisoned money-losing brands during its U.S.-funded reorganization last year.

Now it turns out, according to documents filed with federal regulators, the revamping left the carmaker with another boost as it prepares to return to the stock market. It won't have to pay $45.4 billion in taxes on future profits.

The tax benefit stems from so-called tax-loss carry-forwards and other provisions, which allow companies to use losses in prior years and costs related to pensions and other expenses to shield profits from U.S. taxes for up to 20 years. In GM's case, the losses stem from years prior to when GM entered bankruptcy.

Usually, companies that undergo a significant change in ownership risk having major restrictions put on their tax benefits. The U.S. bailout of GM, in which the Treasury took a 61 percent stake in the company, ordinarily would have resulted in GM having such limits put on its tax benefits, according to tax experts.

But the federal government, in a little-noticed ruling last year, decided that companies that received U.S. bailout money under the Troubled Asset Relief Program won't fall under that rule.

"The Internal Revenue Service has decided that the government's involvement with these companies, both its acquisitions plus its disposals of their stock, means they should be exempt" from the rule, said Robert Willens, a New York tax consultant who advises investment banks and hedge funds.

The government's rationale, said people familiar with the situation, is that the profit-shielding tax credit makes the bailed-out companies more attractive to investors, and that the value of the benefit is greater than the lost tax payments, especially since the tax payments would not exist if the companies fail.

GM declined to comment.

The $45.4 billion in future tax savings consist of $18.9 billion in carry-forwards based on past losses, according to GM's pre-IPO public disclosure. The other tax savings are related to costs such as pensions and other post-retirement benefits, and property, plants and equipment.

The losses were incurred by "Old GM," the company that remained in bankruptcy after the current "New GM" resulted from the reorganization last June.

GM's chief domestic rival, Ford Motor Co., last year adopted a plan to preserve deferred "tax assets" which stood at $17 billion at the end of 2009. Ford can use the tax attributes in certain circumstances to reduce its federal tax liability. Ford declined to comment on the GM tax ruling.