Independent personal services: resident-state taxation ordinarily, but other State may tax with a fixed base or prolonged presence. Income from independent personal services is taxable only in the individual's State of residence except where the individual has a fixed base in the other State, in which case only income attributable to that fixed base may be taxed there, or where the individual's presence in the other State meets the treaty's presence threshold within a 12 month period, in which case only income from activities performed in that other State may be taxed there.