The adjustment, which the company reported Thursday in a filing with the Securities and Exchange Commission, will not affect IBM's gross profit, net income or cash flow for the year, the company said.
The $210 million revision accounted for 0.2 percent of IBM's total revenue last year.
IBM discovered the improprieties after releasing itsin mid-January, the company said. In reviewing agreements for third-party hardware sales in Japan, the company found some IBM Japan employees "acted improperly and inconsistently" with IBM's policies and practices, according to the SEC filing.
The revenue and cost adjustments were made in the first, second and third quarters of the year and affected the company's Global Services unit.
Big Blue's Global Services unit accounted for roughly half of its $96.5 billion in revenue last year.
IBM representatives could not be immediately reached for comment.