1. (a) If any company fails to pay the tax reported to be due on its return within the time specified under the provisions of this chapter, there shall be imposed a penalty equal to ten per cent of such tax due and unpaid or fifty dollars, whichever is greater. Such tax shall bear interest at the rate of one per cent per month or a fraction thereof, from the due date of such tax until the date of payment.
2. (b) If any company has not made its return within one month after the time specified under the provisions of this chapter, the commissioner may make such return at any time thereafter according to the best information obtainable and according to the form prescribed. To the tax imposed upon the basis of such return, there shall be added an amount equal to ten per cent of such tax, or fifty dollars, whichever is greater. No taxpayer shall be subject to a penalty under both subsections (a) and (b) of this section in relation to the same tax period. The tax shall bear interest at the rate of one per cent per month or fraction thereof, from the due date of such tax until the date of payment.
3. (c) Subject to the provisions of section 12-3a, the commissioner may waive all or part of the penalties provided under this chapter when it is proven to his satisfaction that the failure to pay any tax was due to reasonable cause and was not intentional or due to neglect.

(P.A. 80-71, S. 4, 30; P.A. 81-64, S. 21, 23; P.A. 88-314, S. 49, 54; May Sp. Sess. P.A. 94-4, S. 64, 85; P.A. 95-26, S. 30, 52; 95-160, S. 64, 69.)

History: P.A. 80-71 effective July 1, 1980, and applicable to calendar quarters commencing on or after that date; P.A. 81-64 amended penalty provisions to require 10% of the tax or $50 if greater, and to include the waiver of penalty provisions applicable to other state taxes, replacing $25 penalty for failure to file return and penalty of 25% or $50 for failure to pay within three months; P.A. 88-314 restated the penalty provision in Subsec. (a) applicable for failure to pay the tax reported to be due within the time specified and revised the language in Subsec. (b) related to the commissioner's power to prepare a return when not filed within one month after the time specified, adding specific penalties for such case, effective July 1, 1988, and applicable to any tax which first becomes due and payable on or after said date, to any return or report due on or after said date, or in the case of any ongoing obligation imposed in accordance with said act, to the tax period next beginning on or after said date; May Sp. Sess. P.A. 94-4 in Subsec. (b) reduced interest rate from 1.66% to 1% and provided that such interest may only be applied on the tax rather than on the tax and any penalty, effective July 1, 1995, and applicable to taxes due and owing on or after said date; P.A. 95-26 amended Subsec. (a) to lower interest rate from 1.66% to 1%, effective July 1, 1995, and applicable to taxes due and owing on or after July 1, 1995, whether or not those taxes first became due before said date; P.A. 95-160 revised effective date of May Sp. Sess. P.A. 94-4 but without affecting this section.