(a) If the Commissioner is not satisfied that the report filed or the amount of tax paid by a taxpayer is accurate, after investigating and finding such inaccuracy, he or she may make an additional assessment of taxes due from the taxpayer based upon his or her investigation. In estimating the tax due from a licensed user, fuel consumption shall be computed at the rate of 10 miles per gallon for vehicles registered up to and including 10,000 pounds and at four miles per gallon for all vehicles registered over 10,000 pounds for any unreported Vermont mileage in excess of four percent of the operator's total Vermont mileage. Any tax assessed for mileage up to four percent of the operator's total Vermont mileage shall be assessed based on the operator's fuel consumption average for his or her entire fleet. A penalty equal to 10 percent and interest at the rate of one and one-half percent per month shall be payable on the additional assessment, with interest computed from the date the tax payment was due. The Commissioner shall give notice by mail to the taxpayer of the additional assessment, penalty, and interest and shall designate the error or reason for the assessment. Payment shall be due within 30 days of the date of mailing the notice. The Commissioner may, in his or her discretion, waive all or any part of the penalty.

(b) When no report or payment of tax has been made as required by sections 3014 and 3015 of this title, or when a willfully false or fraudulent report has been filed, the tax may be assessed at any time; in all other cases, no assessment of additional tax, and the mailing of notice, shall be made after the expiration of three years from the date of filing a report. (Added 1981, No. 172 (Adj. Sess.), § 1; amended 1985, No. 58, § 3, eff. May 16, 1985; 1987, No. 111, § 3; 1987, No. 241 (Adj. Sess.), § 7; 1999, No. 154 (Adj. Sess.), § 6.)