30 Del. C. § 1170: Filing of estimated tax returns and payment of estimated tax.

(a) The declaration and payment of estimated tax shall be filed or paid, as the case may be, on or before the dates prescribed by the laws of the United States for filing declarations and payment of estimated federal income tax, except that the State Tax Commissioner may establish other dates for filing declarations and payment of estimated tax.

(b) The application of this section to taxable years of less than 12 months shall be in accordance with rules prescribed by the State Tax Commissioner.

(c) Payment of the estimated income tax, or any installment thereof, shall be considered payment on account of the income tax imposed under the provisions of this chapter for the taxable year.