A key question of today's Senate hearing with Apple CEO Tim Cook will be over the financial actions of an Apple subsidiary Apple Operations International. A Senate report shows that Apple, the parent corporation, sent billions of dollars from dividends and profits to Apple Operations International.
This allowed for Apple to exploit several tax rules, known as the check-the-box and look-through rules in order to avoid paying $44 billion in taxes over a four year period legally.
Apple Operations International is by its own description "for tax purposes" and is neither resident in Ireland or the United States.
Expect much of the testimony to focus on the relationship between these two companies.