The Senate wants to know more about Apple's ability to keep billions of dollars in profits free from U.S. taxes.
Apple CEO Tim Cook was called to Capitol Hill on Tuesday to explain the company's use of Irish subsidiaries for tax avoidance.
Committee Chairman Senator Carl Levin said that the use of the Irish subsidiaries helped Apple avoid paying $9 billion in taxes last year.
Cook said Apple does not use gimmicks to avoid taxes, In fact, he said, Apple paid nearly $6 billion to the IRS in 2012 and expects to pay more this year.
Republican Senator John McCain took the middle ground in the discussion, saying that Apple has shifted profits and circumvented U.S. taxes for years - but that the system that allows the practice is flawed.
For comments and feedback: editorial@rttnews.com