(a) General. -- A resident shall be allowed a credit against the tax otherwise due under this article for any income tax imposed for the taxable year by another state of the United States or by the District of Columbia, upon income both derived therefrom and subject to tax under this article.
(b) Limitations. -- (1) The credit under this section shall not exceed the percentage of the tax otherwise due under this article determined by dividing the portion of the taxpayer's West Virginia income subject to taxation by such other jurisdiction by the total amount of the taxpayer's West Virginia income.
(2) The credit under this section shall not reduce the tax otherwise due under this article to an amount less than would have been due if the income subject to taxation by such other jurisdiction were excluded from the taxpayer's West Virginia income.
(c) Exception. -- No credit shall be allowed under this section for a tax of a jurisdiction which allows residents of this state a credit against the taxes imposed by such other jurisdiction for the tax under this article, if such other credit is substantially similar to the credit granted by section forty.
(d) Definition. -- For purposes of this section West Virginia income means:
(1) The West Virginia adjusted gross income of an individual, or
(2) The amount of the income of an estate or trust, determined as if the estate or trust were an individual computing his West Virginia adjusted gross income under section twelve.