(a) Business and occupation tax credit.--A credit shall be allowed against the tax imposed by section three of this article equal to the amount of the liability of the taxpayer for the taxable year for any tax imposed under article thirteen, chapter eleven of this code: Provided, That the amount of such business and occupation tax credit shall not exceed the portion of the tax imposed by this article which is attributable to the West Virginia taxable income derived by the taxpayer for the taxable year from the business or occupation with respect to which said tax under article thirteen was imposed. In case the West Virginia taxable income of a taxpayer includes income from a partnership, estate, trust or a corporation electing to be taxed under subchapter S of the Internal Revenue Code of 1954, as amended, a part of any tax liability of the partnership, estate, trust or corporation under said article thirteen shall be allowed to the taxpayer, in computing the credit provided for by this section, in an amount proportionate to the income of such partnership, estate, trust or corporation, which is included in the taxpayer's West Virginia taxable income.

For purposes of this section, the tax imposed under article thirteen, chapter eleven of this code shall be the amount of the liability of the taxpayer for such tax under said article thirteen computed without reduction for the tax credit for industrial expansion or revitalization allowed for such year.

(b) Severance tax credit.--On and after July 1, 1987, a credit shall be allowed against the tax imposed by section three of this article equal to the amount of the liability of the taxpayer for the taxable year for any tax imposed under article thirteen-a, chapter eleven of this code: Provided, That the amount of such severance tax credit shall not exceed the portion of the tax imposed by this article which is attributable to the West Virginia taxable income derived by the taxpayer for the taxable year from the activities with respect to which said tax under article thirteen-a was imposed. In case the West Virginia taxable income of a taxpayer includes income from a partnership, estate, trust or a corporation electing to be taxed under subchapter S of the Internal Revenue Code of 1954, as amended, a part of any tax liability of the partnership, estate, trust or corporation under said article thirteen-a shall be allowed to the taxpayer, in computing the credit provided for by this section, in an amount proportionate to the income of such partnership, estate, trust or corporation, which is included in the taxpayer's West Virginia taxable income.

(c) Expiration of credit.--The credit authorized in subsection (b) of this section shall expire and not be authorized or allowed for any taxable year beginning on or after October 1, 1990.