(a) such tax, or the balance thereof, shall be payable to the commissioner of finance in full at the time the report is required to be filed; and
(b) such tax, or the balance thereof, imposed on any taxpayer which ceases to do business in the city or to be subject to the tax imposed by this subchapter shall be payable to the commissioner of finance at the time the report is required to be filed; all other taxes of any such taxpayer, which pursuant to the foregoing provisions of this section would otherwise be payable subsequent to the time such report is required to be filed, shall nevertheless be payable at such time. If the taxpayer, within the time prescribed by section 11-655 of this subchapter, shall have applied for an automatic extension of time to file its annual report and shall have paid to the commissioner of finance on or before the date such application is filed an amount properly estimated as provided by said section, the only amount payable in addition to the tax shall be interest at the underpayment rate set by the commissioner of finance pursuant to section 11-687 of this chapter, or, if no rate is set, at the rate of seven and one-half percent per annum upon the amount by which the tax, or the portion thereof payable on or before the date the report was required to be filed, exceeds the amount so paid. For purposes of the preceding sentence:
(1) an amount so paid shall be deemed properly estimated if it is either: (i) not less than ninety percent of the tax as finally determined, or (ii) not less than the tax shown on the taxpayer's report for the preceding taxable year, if such preceding year was a taxable year of twelve months; and
(2) the time when a report is required to be filed shall be determined without regard to any extension of time for filing such report.
2. The commissioner of finance may grant a reasonable extension of time for payment of any tax imposed by this subchapter under such conditions as the commissioner of finance deems just and proper.
3. Intentionally omitted.