(1) General Rule. Every period in which a person engages in business shall be subject to the tax hereby imposed.

(a) Receipts. Every person subject to the payment of the tax hereby imposed shall compute its taxable receipts using the receipts received for the tax measurement year ending in the tax year.

(b) Net income. Every person subject to the payment of the tax hereby imposed shall compute its net income using the net income for the tax measurement year ending in the tax year.

(2) Certain New Businesses. Every person engaging in business that does not have a tax measurement year ending in the tax year shall file a return stating that no tax is due for the tax year.

(3) Terminating Businesses. Every person that has terminated its business during the tax year shall compute its receipts and net income using the period that begins on the beginning date of the tax measurement year ending in the tax year and which ends on the date the business is terminated.

(4) Changes in Tax Measurement Year. The Department shall prescribe regulations to ensure that every person that changes its tax measurement year, including a person that may have multiple tax measurement years within a tax year, shall pay the tax hereby imposed for all periods in business.