1. (a) If the taxpayer files its return for the calendar year on or before February 15th of the succeeding calendar year (or if the taxpayer is on a fiscal-year basis, on or before the 15th day of the second month succeeding the taxable year), and pays therewith the balance, if any, of the full amount of the tax shown to be due on the return:

   1. (1) such return will be considered to be its declaration if no declaration was required to be filed during the taxable year for which the tax was imposed, but a declaration was required to be filed on or before the 15th day of the 12th month of the current taxable year pursuant to section 22-2.3 of this Subpart; or

   2. (2) such return will be considered as the amendment permitted by section 22-2.4 of this Subpart to be filed on or before the 15th day of the 12th month of the current taxable year if the tax shown on the return is greater than the estimate shown on a declaration previously made. Example 1: Example 2:

      Example 1:

      A taxpayer which reports on the basis of a calendar year first meets the requirements for making a declaration of estimated tax on September 5, 1981. The taxpayer may satisfy the requirement for making a declaration of estimated tax by preparing and filing its return for taxable year 1981 on or before February 15, 1982, and paying at the time of filing the balance, if any, of the full amount of tax shown to be payable. The return will be treated as the declaration required to be filed on or before December 15, 1981.

      Example 2:

      The taxpayer makes and files, on or before September 15, 1981, a timely declaration of estimated tax for such year, and on or before February 15, 1982 files its 1981 tax return and pays the balance, if any, of the full amount of tax shown to be payable. If the taxpayer's return shows the tax to be greater than the estimated tax shown on the declaration, the return will be treated as the amended declaration permitted to be filed on or before December 15, 1981.

2. (b) The filing of a declaration or amended declaration or the payment of the last installment of estimated tax on December 15th, or the filing of a return by February 15th of the succeeding calendar year (or if on a fiscal-year basis, on the 15th day of the 12th month of the current taxable year or the 15th day of the second month of the succeeding fiscal year), will not relieve the taxpayer of the additional charge for underpayment of installments if it failed to pay its estimated tax due earlier in its taxable year.

Tax Law, § 1460(e), (f)