(b) Limitations. (1) The credit under this section shall not exceed the percentage of the tax otherwise due under section six hundred three determined by dividing the portion of the taxpayer's ordinary income portion of a lump sum distribution taxable both under section six hundred three and by such other jurisdiction by the total amount of the taxpayer's ordinary income portion of a lump sum distribution taxable under section six hundred three.

(2) The credit under this section shall not reduce the tax otherwise due under section six hundred three to an amount less than would have been due if the portion of the ordinary income portion of a lump sum distribution taxable both under section six hundred three and by such other jurisdiction were excluded from the computation of the separate tax imposed under section six hundred three.

(3) In the case of a taxpayer who elects to claim the foreign tax credit for federal income tax purposes, the credit under this section for income tax imposed by a province of Canada shall be allowed for that portion of the provincial tax not claimed for federal purposes for the taxable year or a preceding taxable year, provided however, to the extent the provincial tax is claimed for federal purposes for a succeeding taxable year, the credit under this section must be added back in such succeeding taxable year. The provincial tax shall be deemed to be claimed last for federal income tax purposes and for purposes of this subsection.