(a) The provisions of sections two-a, two-b, two-c, two-e, two-g, two-h, two-i, two-j, two-k and two-l of this article are inoperative as of July 1, 1987. Persons who are fiscal year taxpayers having a fiscal year ending on June 30, 1987, shall file their annual return for fiscal year 1987, on or before July 31, 1987, and remit the amount of any taxes shown thereon to be due.

(b) Persons who are calendar year taxpayers and who are not subject to the tax imposed by this article for months beginning on or after July 1, 1987, and persons who are fiscal year taxpayers having a fiscal year ending on any date other than June 30, 1987, and who are not subject to the tax imposed by this article for months beginning on or after July 1, 1987, shall file their annual returns on or before July 31, 1987, for the short taxable year which ended June 30, 1987, and remit the amount of any taxes shown thereon to be due. Persons required to file an annual return for a short taxable year may claim a portion of the annual exemption allowed under section three of this article, determined in accordance with the amount of the exemption allowable for each month in the short taxable year. The $5,000 annual exemption allowed to producers of natural gas shall similarly be calculated and allowed on a monthly basis at the rate of $416.66 for each month of the short taxable year ending on June 30, 1987.

(c) Persons engaged in activities taxable under sections two-a, two-b, two-c, two-e, two-g, two-h, two-i, two-j, two-k and two-l of this article prior to July 1, 1987, are taxable under either article thirteen-a or twenty-three of this chapter, or both, on and after such date.

(d) Persons who keep their records using the accrual method of accounting shall file their annual return for the full or short taxable year ending June 30, 1987, computing their tax liability under such method. A taxpayer shall file an amended return for such year and pay any additional taxes due within thirty days after determining that gross income, gross proceeds of sale or gross value were under reported on such annual return, or that any allowable deductions were over reported.

(e) Persons who keep their records using the cash method of accounting may file their annual return for the full or short taxable year ending June 30, 1987, computing their tax liability under such method: Provided, That such a taxpayer shall file a supplemental return for such year within one month after the close of each quarter during which he or she received gross income or gross proceeds of sale for any activity or portion thereof completed prior to July 1, 1987, and pay any additional taxes shown on the supplemental return to be due. The purpose of this requirement is to minimize the advantage or disadvantage associated with the different methods of accounting when the business and occupation tax no longer applies to the taxpayer's ongoing business activity.

(f) Tax liabilities, if any arising for taxable years ending prior to July 1, 1987, shall be determined, administered, assessed and collected as if sections two-a, two-b, two-c, two-e, two-g, two-h, two-i, two-j, two-k and two-l of this article had not been effectively repealed; and the rights and duties of the taxpayer and the State of West Virginia shall be fully and completely preserved.

(g) Persons who keep their records using a method of accounting other than the accrual method or cash method shall file their returns in accordance with regulations and instructions promulgated by the Tax Commissioner.