(b) Definition of estimated tax and estimated tax surcharge. The terms "estimated tax" and "estimated tax surcharge" mean the amounts which the taxpayer estimates to be the taxes imposed by sections fifteen hundred one, fifteen hundred two-a and fifteen hundred ten of this article or the tax surcharge imposed by section fifteen hundred five-a of this article, respectively, for the current taxable year, less the sum of any credits which it estimates to be allowable against such taxes or tax surcharge, respectively.

(c) Time of filing declaration.--A declaration of estimated tax and a declaration of estimated tax surcharge shall be filed on or before June fifteenth of the current taxable year in the case of a taxpayer which reports on the basis of a calendar year, except that if the requirements of subdivision (a) of this section are first met:

(1) after May thirty-first and before September first of such current taxable year the declaration shall be filed on or before September fifteenth, or

(2) after August thirty-first and before December first of such current taxable year, the declaration shall be filed on or before December fifteenth.

(d) Amendments of declaration.--A taxpayer may amend a declaration of estimated tax or a declaration of estimated tax surcharge under regulations prescribed by the commissioner of taxation and finance.

(e) Return as declaration. If, on or before February fifteenth of the succeeding year in the case of a taxpayer whose taxable year is a calendar year, a taxpayer files its return for the year for which the declaration is required, and pays therewith the balance, if any, of the full amount of the tax or tax surcharge shown to be due on the return

(1) such return shall be considered as its declaration if no declaration was required to be filed during the taxable year for which the tax or tax surcharge was imposed, but is otherwise required to be filed on or before December fifteenth pursuant to paragraph two of subdivision (c) of this section, and

(2) such return shall be considered as the amendment permitted by subdivision (d) of this section to be filed on or before December fifteenth if the tax or tax surcharge shown on the return is greater than the estimated tax or estimated tax surcharge, as the case may be, shown on a declaration previously made.

(f) Short taxable period. If the taxable period for which a tax or tax surcharge is imposed under this article is less than twelve months, every taxpayer required to make a declaration of estimated tax or a declaration of estimated tax surcharge for such taxable period shall make such declaration in accordance with rules of the commissioner of taxation and finance.

(g) Fiscal year. The provisions of this section shall apply to taxable years of twelve months other than a calendar year by the substitution of the months of such fiscal year for the corresponding months specified in such provisions.

(h) Extension of time. The tax commission may grant a reasonable extension of time, not to exceed three months, for the filing of any declaration required pursuant to this section, on such terms and conditions as it may require.