26 CFR § 301.6201-1 - Assessment authority.
(a) In general. The district director is authorized and required to make all inquiries necessary to the determination and assessment of all taxes imposed by the Internal Revenue Code of 1954 or any prior internal revenue law. The district director is further authorized and required, and the director of the regional service center is authorized, to make the determinations and the assessments of such taxes. However, certain inquiries and determinations are, by direction of the Commissioner, made by other officials, such as assistant regional commissioners. The term “taxes” includes interest, additional amounts, additions to the taxes, and assessable penalties. The authority of the district director and the director of the regional service center to make assessments includes the following:
(1) Taxes shown on return. The district director or the director of the regional service center shall assess all taxes determined by the taxpayer or by the district director or the director of the regional service center and disclosed on a return or list.
(2) Unpaid taxes payable by stamp.
(i) If without the use of the proper stamp:
(a) Any article upon which a tax is required to be paid by means of a stamp is sold or removed for sale or use by the manufacturer thereof, or
(b) Any transaction or act upon which a tax is required to be paid by means of a stamp occurs;
(ii) If a taxpayer gives a check or money order as a payment for stamps but the check or money order is not paid upon presentment, then the district director or the director of the regional service center shall assess the amount of the check or money order against the taxpayer as if it were a tax due at the time the check or money order was received by the district director.
(3) Erroneous income tax prepayment credits. If the amount of income tax withheld or the amount of estimated income tax paid is overstated by a taxpayer on a return or on a claim for refund, the amount so overstated which is allowed against the tax shown on the return or which is allowed as a credit or refund shall be assessed by the district director or the director of the regional service center in the same manner as in the case of a mathematical error on the return. See section 6213 (b)(1), relating to exceptions to restrictions on assessment.
(b) Estimated income tax. Neither the district director nor the director of the regional service center shall assess any amount of estimated income tax required to be paid under section 6153 or 6154 which is unpaid.
(c) Compensation of child. Any income tax assessed against a child, to the extent of the amount attributable to income included in the gross income of the child solely by reason of section 73(a) or the corresponding provision of prior law, if not paid by the child, shall, for the purposes of the income tax imposed by chapter 1 of the Code (or the corresponding provisions of prior law), be considered as having also been properly assessed against the parent. In any case in which the earnings of the child are included in the gross income of the child solely by reason of section 73(a) or the corresponding provision of prior law, the parent's liability is an amount equal to the amount by which the tax assessed against the child (and not paid by him) has been increased by reason of the inclusion of such earnings in the gross income of the child. Thus, if for the calendar year 1954 the child has income of $1,000 from investments and of $3,000 for services rendered, and the latter amount is includible in the gross income of the child under section 73(a) and the child has no wife or dependents, the tax liability determined under section 3 is $625. If the child had only the investment income of $1,000, his tax liability would be $62. If the tax of $625 is assessed against the child, the difference between $625 and $62, or $563, is the amount of such tax which is considered to have been properly assessed against the parent, if not paid by the child.