@tuxedorose , sorry for the delay in my answer --- generally these adjustments are required for things like foreign capital gains/losses ; for foreign qualified dividends etc. where US has a preferential tax treatment i.e. not taxed at ordinary income tax rate. For most people whom pay foreign taxes at source on income from Mutual funds or similar investments , this adjustment to the foreign gross income is NOT applicable -- so just enter ZERO for adjustment ( TurboTax should require an entry rather than leaving it blank ).
For more details on how to adjust etc. see page 7 of instruction for form 1116. Note that this same form is used for a wide area of foreign tax -- from very simple case like foreign dividend income ( through Mutual Funds or direct ownership of foreign stocks etc.) to very complex foreign investments and incomes, thus making it overly complex for many taxpayers.
pk
