1. (a) If any company fails to pay the amount of tax reported to be due on its return within the time specified under the provisions of this part, there shall be imposed a penalty equal to ten per cent of such amount due and unpaid, or fifty dollars, whichever amount is greater. Such amount 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.
2. (b) If any company has not made its return within three months after the time specified under the provisions of this part, 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. 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. No taxpayer shall be subject to a penalty under both subsections (a) and (b) of this section in relation to the same tax period.
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 on time was due to reasonable cause and was not intentional or due to neglect.

(1949 Rev., S. 1909; 1953, S. 1101d; 1957, P.A. 560, S. 6; 1961, P.A. 369; 1967, P.A. 41, S. 1; P.A. 81-64, S. 5, 23; P.A. 88-314, S. 4, 54; P.A. 93-74, S. 62, 67; May Sp. Sess. P.A. 94-4, S. 33, 85; P.A. 95-160, S. 64, 69; P.A. 00-174, S. 54, 83.)

History: 1961 act added reference to affidavit, and made making of return by commissioner discretionary rather than mandatory; 1967 act clarified applicability of provisions; P.A. 77-614 made “commissioner” refer to commissioner of revenue services rather than tax commissioner, effective January 1, 1979; P.A. 81-64 made penalty previously applicable to those who failed to pay within three months after time specified in Sec. 12-222 applicable in all cases, reducing per cent from 25% to 10%, deleted previous lesser penalty of $25 applicable to cases involving late filing and added waiver provision applicable to other state taxes; P.A. 88-314 provided technical clarification related to penalties imposed when tax is not paid within the time specified and when the commissioner prepares the return, 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; P.A. 93-74 decreased interest rate from 1.66% to 1.25%, effective May 19, 1993, and applicable to taxes due and payable on and after January 1, 1994; May Sp. Sess. P.A. 94-4 in Subsecs. (a) and (b) reduced interest rate from 1.25% 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. 95-160 revised effective date of May Sp. Sess. P.A. 94-4 but without affecting this section; P.A. 00-174 amended Subsec. (a) to delete a reference to affidavit, effective July 1, 2000.