26 U.S.C. § 6201 (INTERNAL REVENUE CODE)
§ 6201. Assessment authority
(a) Authority of Secretary
The Secretary is authorized and required to make the inquiries, determinations, and assessments of all taxes (including interest, additional amounts, additions to the tax, and assessable penalties) imposed by this title, or accruing under any former internal revenue law, which have not been duly paid by stamp at the time and in the manner provided by law. Such authority shall extend to and include the following:
(1) Taxes shown on return
The Secretary shall assess all taxes determined by the taxpayer or by the Secretary as to which returns or lists are made under this title.
(2) Unpaid taxes payable by stamp
(A) Omitted stamps
Whenever 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 whenever any transaction or act upon which a tax is required to be paid by means of a stamp occurs without the use of the proper stamp, it shall be the duty of the Secretary, upon such information as he can obtain, to estimate the amount of tax which has been omitted to be paid and to make assessment therefor upon the person or persons the Secretary determines to be liable for such tax.
(B) Check or money order not duly paid
In any case in which a check or money order received under authority of section 6311 as payment for stamps is not duly paid, the unpaid amount may be immediately assessed as if it were a tax imposed by this title, due at the time of such receipt, from the person who tendered such check or money order.
(3) Erroneous income tax prepayment credits
If on any return or claim for refund of income taxes under subtitle A there is an overstatement of the credit for income tax withheld at the source, or of the amount paid as estimated income tax, the amount so overstated which is allowed against the tax shown on the return or which is allowed as a credit or refund may be assessed by the Secretary in the same manner as in the case of a mathematical or clerical error appearing upon the return, except that the provisions of section 6213(b)(2) (relating to abatement of mathematical or clerical error assessments) shall not apply with regard to any assessment under this paragraph.
(4) Certain orders of criminal restitution
(A) In general
The Secretary shall assess and collect the amount of restitution under an order pursuant to section 3556 of title 18, United States Code, for failure to pay any tax imposed under this title in the same manner as if such amount were such tax.
(B) Time of assessment
An assessment of an amount of restitution under an order described in subparagraph (A) shall not be made before all appeals of such order are concluded and the right to make all such appeals has expired.
(C) Restriction on challenge of assessment
The amount of such restitution may not be challenged by the person against whom assessed on the basis of the existence or amount of the underlying tax liability in any proceeding authorized under this title (including in any suit or proceeding in court permitted under section 7422).
(b) Amount not to be assessed
(1) Estimated income tax
No unpaid amount of estimated income tax required to be paid under section 6654 or 6655 shall be assessed.
(2) Federal unemployment tax
No unpaid amount of Federal unemployment tax for any calendar quarter or other period of a calendar year, computed as provided in section 6157, shall be assessed.
(c) Compensation of child
Any income tax under chapter 1 assessed against a child, to the extent attributable to amounts includible in the gross income of the child, and not of the parent, solely by reason of section 73(a), shall, if not paid by the child, for all purposes be considered as having also been properly assessed against the parent.
(d) Required reasonable verification of information returns
In any court proceeding, if a taxpayer asserts a reasonable dispute with respect to any item of income reported on an information return filed with the Secretary under subpart B or C of part III of subchapter A of chapter 61 by a third party and the taxpayer has fully cooperated with the Secretary (including providing, within a reasonable period of time, access to and inspection of all witnesses, information, and documents within the control of the taxpayer as reasonably requested by the Secretary), the Secretary shall have the burden of producing reasonable and probative information concerning such deficiency in addition to such information return.
(e) Deficiency proceedings
For special rules applicable to deficiencies of income, estate, gift, and certain excise taxes, see subchapter B.
(Aug. 16, 1954, ch. 736, 68A Stat. 767; Pub. L. 89–44, title VIII, § 809(d)(4)(A), June 21, 1965, 79 Stat. 168; Pub. L. 91–53, § 2(b), Aug. 7, 1969, 83 Stat. 92; Pub. L. 91–172, title I, § 101(j)(38), Dec. 30, 1969, 83 Stat. 530; Pub. L. 91–258, title II, § 207(d)(1), (2), May 21, 1970, 84 Stat. 248; Pub. L. 93–406, title II, § 1016(a)(8), Sept. 2, 1974, 88 Stat. 929; Pub. L. 94–12, title II, § 204(b)(2), Mar. 29, 1975, 89 Stat. 31; Pub. L. 94–455, title XII, § 1206(c)(2), title XIII, § 1307(d)(2)(D), title XIX, § 1906(b)(13)(A), Oct. 4, 1976, 90 Stat. 1704, 1727, 1834; Pub. L. 97–424, title V, § 515(b)(6)(E), Jan. 6, 1983, 96 Stat. 2182; Pub. L. 98–76, title II, § 231(b)(2)(A), Aug. 12, 1983, 97 Stat. 429; Pub. L. 98–369, div. A, title IV, §§ 412(b)(5), 474(r)(32), July 18, 1984, 98 Stat. 792, 845; Pub. L. 100–203, title X, § 10301(b)(3), Dec. 22, 1987, 101 Stat. 1330–429; Pub. L. 100–647, title I, § 1015(r)(1), title VII, § 7106(c)(2), Nov. 10, 1988, 102 Stat. 3572, 3773; Pub. L. 104–168, title VI, § 602(a), July 30, 1996, 110 Stat. 1463; Pub. L. 111–237, § 3(a), Aug. 16, 2010, 124 Stat. 2497.)
heading: Amendments
text: 2010—Subsec. (a)(4). Pub. L. 111–237 added par. (4).
1996—Subsecs. (d), (e). Pub. L. 104–168 added subsec. (d) and redesignated former subsec. (d) as (e).
1988—Subsec. (a)(4). Pub. L. 100–647, § 1015(r)(1), struck out par. (4) which read as follows: “If on any return or claim for refund of income taxes under subtitle A there is an overstatement of the credit allowable by section 34 (relating to certain uses of gasoline and special fuels) or section 32 (relating to earned income), the amount so overstated which is allowed against the tax shown on the return or which is allowed as a credit or refund may be assessed by the Secretary in the same manner as in the case of a mathematical or clerical error appearing upon the return, except that the provisions of section 6213(b)(2) (relating to abatement of mathematical or clerical error assessments) shall not apply with regard to any assessment under this paragraph.”
Subsec. (b)(2). Pub. L. 100–647, § 7106(c)(2), struck out “or tax imposed by section 3321” after “employment tax”.
1987—Subsec. (b)(1). Pub. L. 100–203 substituted “section 6654 or 6655” for “section 6154 or 6654”.
1984—Subsec. (a)(4). Pub. L. 98–369, § 474(r)(32), substituted “section 32 or 34” for “section 39 or 43” in heading, and in text substituted “section 34” for “section 39” and “section 32” for “section 43”.
Subsec. (b)(1). Pub. L. 98–369, § 412(b)(5), amended par. (1) generally, substituting “estimated income tax required to be paid under section 6154 or 6654” for “estimated tax under section 6153 or 6154”.
1983—Subsec. (a)(4). Pub. L. 97–424 substituted “and special fuels” for “, special fuels, and lubricating oil” after “gasoline”.
Subsec. (b)(2). Pub. L. 98–76 substituted “Federal unemployment tax or tax imposed by section 3321” for “Federal unemployment tax”.
1976—Subsec. (a). Pub. L. 94–455, § 1906(b)(13)(A), struck out “or his delegate” after “Secretary”.
Subsec. (a)(3), (4). Pub. L. 94–455, §§ 1206(c)(2), 1906(b)(13)(A), struck out “or his delegate” after “Secretary”, substituted “mathematical or clerical error” for “mathematical error” after “the case of”, and inserted “, except that the provisions of section 6213(b)(2) (relating to abatement of mathematical or clerical error assessments) shall not apply with regard to any assessment under this paragraph” after “upon the return”.
Subsec. (d). Pub. L. 94–455, § 1307(d)(2)(D), substituted “and certain excise taxes” for “chapter 42, and chapter 43 taxes” after “estate, gift”.
1975—Subsec. (a)(4). Pub. L. 94–12 inserted reference to section 43 in heading and substituted “oil) or section 43 (relating to earned income),” for “oil),” in text.
1974—Subsec. (d). Pub. L. 93–406 inserted reference to chapter 43 taxes.
1970—Subsec. (a)(4). Pub. L. 91–258 inserted provision for overstatement of credit allowable by section 39 (relating to certain uses of special fuels) in text and substituted “under section 39” for “for use of gasoline” in heading.
1969—Subsec. (b). Pub. L. 91–53 added subsec. (b) heading and par. (2), and redesignated former subsec. (b), including its heading, as par. (1).
Subsec. (d). Pub. L. 91–172 inserted reference to chapter 42 taxes.
1965—Subsec. (a)(4). Pub. L. 89–44 added par. (4).
heading: Effective Date of 2010 Amendment
text: Pub. L. 111–237, § 3(c), Aug. 16, 2010, 124 Stat. 2498, provided that: “The amendments made by this section [amending this section and sections 6213 and 6501 of this title] shall apply to restitution ordered after the date of the enactment of this Act [Aug. 16, 2010].”
heading: Effective Date of 1996 Amendment
text: Pub. L. 104–168, title VI, § 602(b), July 30, 1996, 110 Stat. 1463, provided that: “The amendment made by subsection (a) [amending this section] shall take effect on the date of the enactment of this Act [July 30, 1996].”
heading: Effective Date of 1988 Amendment
text: Pub. L. 100–647, title I, § 1015(r)(4), Nov. 10, 1988, 102 Stat. 3573, provided that: “The amendments made by this subsection [amending this section and sections 6211 and 6213 of this title] shall apply to notices of deficiencies mailed after the date of the enactment of this Act [Nov. 10, 1988].”
Amendment by section 7106(c)(2) of Pub. L. 100–647 applicable to remuneration paid after Dec. 31, 1988, see section 7106(d) of Pub. L. 100–647, set out as a note under section 3321 of this title.
heading: Effective Date of 1987 Amendment
text: Amendment by Pub. L. 100–203 applicable to taxable years beginning after Dec. 31, 1987, see section 10301(c) of Pub. L. 100–203, set out as a note under section 585 of this title.
heading: Effective Date of 1984 Amendment
text: Amendment by section 412(b)(5) of Pub. L. 98–369 applicable with respect to taxable years beginning after Dec. 31, 1984, see section 414(a)(1) of Pub. L. 98–369, set out as a note under section 6654 of this title.
Amendment by section 474(r)(32) of Pub. L. 98–369 applicable to taxable years beginning after Dec. 31, 1983, and to carrybacks from such years, see section 475(a) of Pub. L. 98–369, set out as a note under section 21 of this title.
heading: Effective Date of 1983 Amendment
text: Amendment by Pub. L. 98–76 applicable to remuneration paid after June 30, 1986, see section 231(d) of Pub. L. 98–76, set out as an Effective Date note under section 3321 of this title.
Amendment by Pub. L. 97–424 applicable with respect to articles sold after Jan. 6, 1983, see section 515(c) of Pub. L. 97–424, set out as a note under section 34 of this title.
heading: Effective Date of 1976 Amendment
text: Amendment by section 1206(c)(2) of Pub. L. 94–455 applicable with respect to returns filed after Dec. 31, 1976, see section 1206(d) of Pub. L. 94–455, set out as a note under section 6213 of this title.
Amendment by section 1307(d)(2)(D) of Pub. L. 94–455 effective on and after Oct. 4, 1976, see section 1307(e) of Pub. L. 94–455, set out as a note under section 501 of this title.
heading: Effective Date of 1975 Amendment
text: Amendment by Pub. L. 94–12 applicable to taxable years beginning after Dec. 31, 1974, see section 209(b) of Pub. L. 94–12, as amended, set out as a note under section 32 of this title.
heading: Effective Date of 1974 Amendment
text: Amendment by Pub. L. 93–406 applicable, except as otherwise provided in section 1017(c) through (i) of Pub. L. 93–406, for plan years beginning after Sept. 2, 1974, but, in the case of plans in existence on Jan. 1, 1974, amendment by Pub. L. 93–406 applicable for plan years beginning after Dec. 31, 1975, see section 1017 of Pub. L. 93–406, set out as an Effective Date; Transitional Rules note under section 410 of this title.
heading: Effective Date of 1970 Amendment
text: Amendment by Pub. L. 91–258 effective July 1, 1970, see section 211(a) of Pub. L. 91–258, set out as a note under section 4041 of this title.
heading: Effective Date of 1969 Amendments
text: Amendment by Pub. L. 91–172 effective Jan. 1, 1970, see section 101(k)(1) of Pub. L. 91–172, set out as an Effective Date note under section 4940 of this title.
Amendment by Pub. L. 91–53 applicable with respect to calendar years beginning after Dec. 31, 1969, see section 4(a) of Pub. L. 91–53, set out as an Effective Date note under section 6157 of this title.
heading: Effective Date of 1965 Amendment
text: Amendment by Pub. L. 89–44 applicable to taxable years beginning on or after July 1, 1965, see section 809(f) of Pub. L. 89–44, set out as a note under section 6420 of this title.