The tax imposed by this chapter shall be payable as follows:

(1) Calendar year corporations. — a. Except as provided in paragraph (1)b. of this section, 50% of the estimated tax liability for the current taxable year shall be paid with the tentative return filed on April 15 of the current taxable year, and the balance of the estimated tax shall be paid in 3 installments as follows: 20% on June 15 of the current taxable year; 20% on September 15 of the current taxable year; and 10% on December 15 of the current taxable year.

b. For small corporations, 25% of the estimated tax liability for the current taxable year shall be paid with the tentative return filed on April 15 of the current taxable year, and the balance of the estimated tax shall be paid in 3 equal installments of 25% on each of June 15, September 15, and December 15 of the current taxable year.

(2) Fiscal year corporations. — a. Except as provided in paragraph (2)b. of this section, 50% of the estimated tax liability for the current taxable year shall be paid with the tentative return filed on the fifteenth day of the fourth month of the current taxable year, and the balance of the estimated tax shall be paid in 3 installments as follows: 20% on the fifteenth day of the sixth month of the current taxable year; 20% on the fifteenth day of the ninth month of the current taxable year; and 10% on the fifteenth day of the twelfth month of the current taxable year.

b. For small corporations, 25% of the estimated tax liability for the current taxable year shall be paid with the tentative return filed on the fifteenth day of the fourth month of the current taxable year, and the balance of the estimated tax shall be paid in 3 equal installments of 25% on each of the fifteenth day of the sixth month of the current taxable year; the fifteenth day of the ninth month of the current taxable year; and the fifteenth day of the twelfth month of the current taxable year.

(3) Additional taxes due on final return. —

Any additional tax due as computed in the final return required to be filed pursuant to § 1904 of this title shall be paid with such final return.

(4) Tentative tax declarations and payments are not required for returns for taxable periods of less than 92 calendar days.

(5) For purposes of this section, the term “small corporation” means any corporation, including, without limitation, an S corporation subject to § 1158 of this title, if such corporation (or any predecessor corporation) had aggregate gross receipts from sales of tangible personal property and gross income from other sources both within and without the State for purposes of computing the ratio described in § 1903(b)(6)b.3. of this title that do not exceed the applicable threshold of $20,000,000 for any 2 of the 3 taxable years immediately preceding the taxable year for which estimated tax is being computed. (The applicable threshold in this subsection is subject to annual adjustment as more fully set forth in § 515 of this title.)

30 Del. C. 1953, § ?1905; 51 Del. Laws, c. 298; 51 Del. Laws, c. 315, § ?5; 60 Del. Laws, c. 15, § ?1; 60 Del. Laws, c. 193, § ?1; 71 Del. Laws, c. 217, § ?7; 80 Del. Laws, c. 195, § 10; 81 Del. Laws, c. 19, § 6;