1. (a) Estimate; failure to file return. If any person fails to make a return, the commissioner shall make an estimate of the amount of the gross receipts of the person or, as the case may be, of the amount of the total sales price of services or tangible personal property sold or purchased by the person, the storage, acceptance, consumption or other use of which in this state is subject to the use tax. The estimate shall be made for the period or periods in respect to which the person failed to make a return and shall be based upon any information which is in or may come into the commissioner's possession. To the tax imposed upon the basis of such estimate, there shall be added an amount equal to fifteen per cent of such tax, or fifty dollars, whichever is greater. No person shall be subject to a penalty under both this section and section 12419. The commissioner may make more than one assessment for a tax period for which a tax return has not been filed.
2. (b) Interest. The amount of the assessment shall bear interest at the rate of one per cent per month or fraction thereof from the last day of the month succeeding the period for which the amount or any portion thereof should have been returned until the date of payment.
3. (c) Notice of estimate, assessment and penalty. Promptly after making the assessment, the commissioner shall give to the person written notice of the estimate, assessment and penalty, the notice to be served personally or by mail in the manner prescribed for service of notice of a deficiency assessment.
4. (d) Issuance of deficiency assessment or reassessment. Nothing in this section shall preclude the commissioner from issuing a deficiency assessment or reassessment pursuant to the provisions of section 12-415 for any period for which the commissioner issues a written notice of estimate, assessment and penalty under this section.

(1949 Rev., S. 2100; March, 1958, P.A. 27, S. 20; 1969, P.A. 388, S. 11, 12; P.A. 75-213, S. 37, 53; Dec. Sp. Sess. P.A. 75-1, S. 7, 12; P.A. 76-322, S. 12, 13, 27; P.A. 80-307, S. 20, 21, 31; P.A. 81-64, S. 8, 9, 23; 81-411, S. 28, 29, 42; P.A. 85-316, S. 3, 7; P.A. 88-314, S. 26, 54; P.A. 90-148, S. 11, 34; May Sp. Sess. P.A. 94-4, S. 39, 76, 85; P.A. 95-160, S. 64, 69; P.A. 97-243, S. 29, 67; P.A. 99-48, S. 7, 10; P.A. 22-117, S. 22.)

History: 1969 act increased interest rates in Subsecs. (2) and (3) from 0.5% to 0.75%; P.A. 75-213 added references to “acceptance” and “services” in Subsec. (1); Dec. Sp. Sess. P.A. 75-1 deleted “quarterly” with reference to payment period in Subsec. (3), effective January 1, 1976, and applicable to taxes imposed by chapter 219 on or after that date; P.A. 76-322 increased interest rates in Subsecs. (2) and (3) to 1%; P.A. 80-307 temporarily increased interest rates in Subsecs. (2) and (3) to 1.25% for payments and assessments due on or after July 1, 1980, but not later than June 30, 1981; P.A. 81-64 amended Subsec. (1) to include a minimum penalty of $50, and amended Subsec. (4) to include waiver of penalty provision applicable to other state taxes; P.A. 81-411 continued interest applicable to overpayments and underpayments related to assessment by the commissioner under Subsec. (2) at 1.25% per month, and continued interest applicable to an assessment by the commissioner under Subsec. (3) at the rate of 1.25% per month, effective July 1, 1981, and applicable to taxes becoming due on or after that date; P.A. 85-316 amended Subsec. (2) by deleting reference to penalties on underpayments as an item against which overpayments may be offset, retaining interest on underpayments as an item subject to such offset; P.A. 88-314 amended Subsec. (1) by a restatement of the commissioner's estimate of tax when no return is filed and the penalty to be added thereto, and deleted Subsec. (4) concerning failure of any person to file a return due to fraud or intent to evade the tax and the applicable penalties because this provision is covered in another section of chapter 219, 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. 90-148 increased the rate of penalty added in Subsec. (1) from 10% to 15% of the tax and increased the rate of interest applicable under Subsecs. (2) and (3) from 1.25% to 1.66% per month, effective July 1, 1990, and applicable to taxes becoming due on or after that date; May Sp. Sess. P.A. 94-4 made existing Subsec. (1) a Subdiv. (A) and added provision that commissioner may not make more than one assessment for a tax period and added a new Subdiv. (B) re supplemental assessment, effective June 9, 1994, and in Subsecs. (2) and (3) reduced interest rate from 1.66% to 1%, 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. 97-243 amended Subsec. (1) to allow commissioner to make more than one assessment if new information comes into his possession and deleted requirement to adopt regulations, effective July 1, 1997; P.A. 99-48 replaced numeric Subsec. indicators with alphabetic indicators, deleting former Subsec. (2) re offsets by the commissioner, and made technical changes, effective January 1, 2000; P.A. 22-117 amended Subsec. (a) to replace prohibition on commissioner making more than 1 assessment for tax period for which return has not been filed except in case of new information coming into commissioner's possession with provision authorizing commissioner to make more than 1 assessment for tax period for which return has not been filed, and add Subsec. (d) re issuance of deficiency assessment or reassessment pursuant to Sec. 12-415, effective May 27, 2022.