For years, federal investigators have been scrutinizing Caterpillar’s overseas tax affairs with no resolution to the examinations of the complex maneuvers involving billions of dollars and one of the company’s Swiss subsidiaries.

Now, a report commissioned by the government and reviewed by The New York Times accuses the heavy-equipment maker of carrying out tax and accounting fraud. It is extremely rare to accuse a big multinational company of tax fraud, which could result in high penalties.

“Caterpillar did not comply with either U.S. tax law or U.S. financial reporting rules,” wrote Leslie A. Robinson, an accounting professor at the Tuck School of Business at Dartmouth College and the author of the report. “I believe that the company’s noncompliance with these rules was deliberate and primarily with the intention of maintaining a higher share price. These actions were fraudulent rather than negligent.”

No charges have been filed, and it is not clear whether investigators agree with the findings or intend to act on them. The report, which has not been made public or made available to Caterpillar, outlines a company strategy for bringing home billions of dollars from offshore affiliates while avoiding federal income taxes on those earnings.