§ 116. Payments of estimated tax. (a) General.--The estimated tax
with respect to which a declaration is required shall be paid as
follows:

(1) If the declaration is filed on or before April fifteenth of the
taxable year, the estimated tax shall be paid in four equal
installments. The first installment shall be paid at the time of the
filing of the declaration, and the second, third and fourth installments
shall be paid on the following June fifteenth, September fifteenth, and
January fifteenth, respectively.

(2) If the declaration is filed after April fifteenth and not after
June fifteenth of the taxable year, and is not required to be filed on
or before April fifteenth of the taxable year, the estimated tax shall
be paid in three equal installments. The first installment shall be paid
at the time of the filing of the declaration, and the second and third
installments shall be paid on the following September fifteenth and
January fifteenth, respectively.

(3) If the declaration is filed after June fifteenth and not after
September fifteenth of the taxable year, and is not required to be filed
on or before June fifteenth of the taxable year, the estimated tax shall
be paid in two equal installments. The first installment shall be paid
at the time of the filing of the declaration, and the second shall be
paid on the following January fifteenth.

(4) If the declaration is filed after September fifteenth of the
taxable year, and is not required to be filed on or before September
fifteenth of the taxable year, the estimated tax shall be paid in full
at the time of the filing of the declaration.

(5) If the declaration is filed after the time prescribed therefor, or
after the expiration of any extension of time therefor, paragraphs (2),
(3) and (4) of this subdivision shall not apply, and there shall be paid
at the time of such filing all installments of estimated tax payable at
or before such time, and the remaining installments shall be paid at the
times at which, and in the amounts in which, they would have been
payable if the declaration had been filed when due.

(b) Amendments of declaration.--If any amendment of a declaration is
filed, the remaining installments, if any, shall be ratably increased or
decreased (as the case may be) to reflect any increase or decrease in
the estimated tax by reason of such amendment, and if any amendment is
made after September fifteenth of the taxable year, any increase in the
estimated tax by reason thereof shall be paid at the time of making such
amendment.

(c) Application to short taxable year.--This section shall apply to a
taxable year of less than twelve months in accordance with regulations
of the director of finance.

(d) Fiscal year.--This section shall apply to a taxable year other
than a calendar year by the substitution of the months of such fiscal
year for the corresponding months specified in this section.

(e) Installments paid in advance.--An unincorporated business may
elect to pay any installment of its estimated tax prior to the date
prescribed for the payment thereof.

(f) Cross reference.--For unincorporated businesses with taxable years
beginning prior to the date that this title becomes effective, see
subdivision (j) of section one hundred fifteen.

(g) The portion of an overpayment attributable to a credit allowable
pursuant to subdivision (c) of section one hundred one of of this
chapter may not be credited against any payment due under this section.