26 U.S.C. § 6501 — Limitations on assessment and collection

(a) General rule. Unless this section provides an exception, the amount of any tax imposed by this title must be assessed within 3 years after the taxpayer files the return, even if the taxpayer filed it before or after the required date. If the tax is payable by stamp, it may be assessed after the tax becomes due and before 3 years have passed since any part of the tax was paid. A court case to collect the tax without an assessment must also begin before that period ends. In this chapter, “return” means the return the taxpayer is required to file. It does not include a return filed by someone from whom the taxpayer received an item of income, gain, loss, deduction, or credit. This section does not define “tax,” “income,” “gain,” “loss,” “deduction,” or “credit.” (b) Time return deemed filed. (1) Early return. For a tax under this title, other than a tax under chapters 3, 4, 21, or 24, a return filed before the last date set by law or regulation is treated, for this section, as filed on that last date. (2) Return of certain employment and withholding taxes. If a return for a period ending in, or within, a calendar year concerns a tax under chapter 3, 4, 21, or 24 and is filed before April 15 of the following calendar year, it is treated as filed on April 15 of that following calendar year. (3) Return executed by Secretary. Even though section 6020(b)(2) provides otherwise, the Secretary’s execution of a return under section 6020(b) does not start the assessment-and-collection limitation period. (4) Return of excise taxes. For a tax under subtitle D, filing a return for a specified period on which an entry is made for that tax—including an entry showing no liability—counts as filing a return for all amounts of that tax for that period that would have to be reported if properly paid. (c) Exceptions. (1) False return. If a return is false or fraudulent and was made with intent to evade tax, the tax may be assessed at any time. A court case to collect it without an assessment may also begin at any time. (2) Willful attempt to evade tax. If a person willfully attempts in any manner to defeat or evade a tax imposed by this title, other than a tax imposed by subtitle A or subtitle B, the tax may be assessed at any time. A court case to collect it without an assessment may also begin at any time. This subsection therefore applies to taxes other than those imposed by subtitles A or B; this section does not define “defeat” or “evade.” (3) No return. If the taxpayer fails to file a return, the tax may be assessed at any time, and a court case to collect it without an assessment may begin at any time. (4) Extension by agreement. (A) In general. Before the assessment period ends for a tax under this title, other than the estate tax under chapter 11, the Secretary and the taxpayer may agree in writing that the tax may be assessed after that period. The tax may then be assessed before the agreed period ends. Before the agreed period ends, later written agreements may extend the period again. (B) Notice to taxpayer of right to refuse or limit extension. Each time the Secretary asks for this consent, the Secretary must tell the taxpayer that the taxpayer may refuse to extend the limitation period or may limit the extension to particular issues or a particular amount of time. (5) Tax resulting from changes in certain income tax or estate tax credits. Special rules apply when changing certain taxes allowed as credits against income tax or estate tax creates additional tax. The rules are in section 905(c) for the foreign tax credit for income-tax purposes and section 2016 for foreign-country, State, and similar taxes claimed as credits against estate tax. (6) Termination of private foundation status. For the tax on ending private-foundation status under section 507, the tax may be assessed at any time, and a court case to collect it without an assessment may begin at any time. (7) Special rule for certain amended returns. If, during the 60 days ending on the day the normal assessment period for a subtitle A tax for a taxable year would end, the Secretary receives a written document signed by the taxpayer showing that the taxpayer owes more of that tax for that year, the assessment period for the additional amount cannot end before 60 days after the Secretary receives the document. (8) Failure to notify Secretary of certain foreign transfers. (A) In general. If information must be reported to the Secretary because of an election under section 1295(b) or under section 1298(f), 6038, 6038A, 6038B, 6038D, 6046, 6046A, or 6048, the assessment period for any tax under this title relating to the return, event, or period covered by that information cannot end before 3 years after the Secretary is given the required information. (B) Application to failures due to reasonable cause. If the failure to provide the information was caused by reasonable cause and not willful neglect, subparagraph (A) applies only to the item or items related to that failure. (9) Gift tax on certain gifts not shown on return. If a gift of property whose value must be shown on a chapter 12 gift-tax return is not shown on that return, the chapter 12 tax on that gift may be assessed at any time, and a court case to collect it without an assessment may begin at any time. The same rule applies to an increase in taxable gifts required under section 2701(d), without regard to section 2503(b). This rule does not apply to an item disclosed in the return or an attached statement in enough detail to tell the Secretary the item’s nature. (10) Listed transactions. If a taxpayer fails to include on a return or statement for a taxable year information about a “listed transaction” that section 6011 requires to be included, the assessment period for any tax under this title relating to that transaction cannot end before 1 year after the earlier of—(A) the date the Secretary receives the required information; or (B) the date a material advisor satisfies section 6112 in response to the Secretary’s request under section 6112(b) concerning that transaction and taxpayer. Section 6707A(c)(2) defines “listed transaction”; this section does not define it. (11) Certain orders of criminal restitution. An amount described in section 6201(a)(4) may be assessed at any time, and a court case to collect it without an assessment may begin at any time. (12) Certain taxes attributable to partnership adjustments. For a partnership adjustment determined under subchapter C of chapter 63, the assessment period for a chapter 2 or chapter 2A tax attributable to that adjustment cannot end before 1 year after—(A) if a court decision in a proceeding under section 6234 caused the adjustment, the decision becomes final; or (B) in any other case, 90 days after the notice of the final partnership adjustment is mailed under section 6231. This section does not define “partnership adjustment.” (d) Request for prompt assessment. Unless subsection (c), (e), or (f) provides otherwise, this rule applies to any tax other than the estate tax under chapter 11 of subtitle B for which a return is required from a decedent, the decedent’s estate during administration, or a corporation. After the executor, administrator, other fiduciary representing the estate, or corporation makes a written request after the return has been made and filed in the form and manner required by the Secretary’s regulations, the tax must be assessed and any court case to collect it without an assessment must begin within 18 months after the request. But neither may occur after 3 years after the return was filed. For a corporation, this rule applies only if—(1)(A) the request tells the Secretary that the corporation expects to dissolve at or before the 18-month period ends, (B) the dissolution is begun in good faith before that period ends, and (C) the dissolution is completed; (2)(A) the request tells the Secretary that a dissolution has been begun in good faith, and (B) the dissolution is completed; or (3) the dissolution was complete when the request was made. (e) Substantial omission of items. Unless subsection (c) provides otherwise—(1) Income taxes. For a tax under subtitle A—(A) General rule. If the taxpayer leaves out from gross income an amount that should have been included, the tax may be assessed, or a court case to collect it without an assessment may begin, within 6 years after the return was filed if—(i) the omitted amount is more than 25 percent of the gross income stated in the return; or (ii) the amount—(I) is attributable to one or more assets for which information must be reported under section 6038D, or would have to be reported if the dollar threshold in section 6038D(a) and the exceptions under section 6038D(h)(1) did not apply, and (II) is more than $5,000. (B) Determination of gross income. For subparagraph (A)—(i) for a trade or business, “gross income” means all amounts received or accrued from selling goods or services, when those amounts must be shown on the return, before subtracting the cost of those goods or services; (ii) understating gross income because unrecovered cost or another basis was overstated counts as leaving out gross income; and (iii) except when the omission results from overstating unrecovered cost or another basis, an amount left out of the gross income stated in the return is not counted if the return or an attached statement discloses it in enough detail to tell the Secretary its nature and amount. (C) Amount includible under section 951(a). If the taxpayer leaves out from gross income an amount that should have been included under section 951(a), the tax may be assessed, or a court case to collect it without an assessment may begin, within 6 years after the return was filed. (2) Estate and gift taxes. For an estate-tax return under chapter 11 or a gift-tax return under chapter 12, if the taxpayer leaves out from the gross estate or from the total gifts made during the return period items that should have been included, and the omitted items exceed 25 percent of the gross estate or total gifts stated in the return, the tax may be assessed, or a court case to collect it without an assessment may begin, within 6 years after the return was filed. An omitted item is not counted if the return or an attached statement discloses it in enough detail to tell the Secretary its nature and amount. (3) Excise taxes. For a return of a tax under subtitle D, if the return leaves out an amount of tax that should have been included and that amount is more than 25 percent of the tax reported on the return, the tax may be assessed, or a court case to collect it without an assessment may begin, within 6 years after the return was filed. When calculating the omitted tax, do not count an amount under chapters 41, 42, 43, or 44 if the return or an attached statement discloses the transaction producing the tax in enough detail to tell the Secretary the item’s existence and nature. (f) Personal holding company tax. If a corporation is a “personal holding company” for a taxable year and does not file with its chapter 1 return a schedule listing—(1) the corporation’s gross-income and adjusted-ordinary-gross-income items described in section 543 that it received during the year; and (2) the names and addresses of individuals who, within the meaning of section 544, owned more than 50 percent in value of the corporation’s outstanding capital stock at any time during the last half of the year—the personal holding company tax for that year may be assessed, or a court case to collect it without an assessment may begin, within 6 years after the return was filed. This section does not define “personal holding company,” “gross income,” or “adjusted ordinary gross income.” (g) Certain income tax returns of corporations. (1) Trusts or partnerships. If a taxpayer in good faith determines that it is a trust or partnership and files a subtitle A return as one, but is later held to be a corporation for that taxable year, that return is treated as the corporation’s return for this section. (2) Exempt organizations. If a taxpayer in good faith determines that it is an exempt organization and files a return under section 6033 as one, but is later held to be a taxable organization for that taxable year, that return is treated as the organization’s return for this section. (3) DISC. If a corporation in good faith determines that it is a DISC, as defined in section 992(a), and files a return as one under section 6011(c)(2), but is later held to be a corporation that is not a DISC for that taxable year, that return is treated as the return of a corporation that is not a DISC for this section. This section does not define “trust,” “partnership,” “exempt organization,” “taxable organization,” or “DISC.” (h) Net operating loss or capital loss carrybacks. If a deficiency results from applying to the taxpayer a net operating loss carryback or capital loss carryback, including a deficiency that may be assessed under section 6213(b)(3), the deficiency may be assessed before the assessment period ends for a deficiency for the taxable year of the net operating loss or net capital loss that created the carryback. (i) Foreign tax carrybacks. If a deficiency results from applying to the taxpayer a carryback under section 904(c), concerning excess foreign taxes carried back or forward, or section 907(f), concerning disallowed foreign oil and gas taxes carried back or forward, the deficiency may be assessed before 1 year after the assessment period ends for a deficiency for the taxable year of the excess taxes under section 904(c) or section 907(f) that created the carryback. (j) Certain credit carrybacks. (1) In general. If a deficiency results from applying a “credit carryback” to the taxpayer, including a deficiency that may be assessed under section 6213(b)(3), the deficiency may be assessed before the assessment period ends for a deficiency for the taxable year of the unused credit that created the carryback. For any part of a credit carryback from a taxable year that came from a net operating loss carryback, capital loss carryback, or another credit carryback from a later taxable year, the deficiency may instead be assessed before the assessment period ends for a deficiency for that later taxable year. (2) Credit carryback defined. For this subsection, “credit carryback” has the meaning given in section 6511(d)(4)(C). This section does not define that term. (k) Tentative carryback adjustment assessment period. If an amount was applied, credited, or refunded under section 6411 because a net operating loss carryback, capital loss carryback, or credit carryback was applied to a prior taxable year, the period in subsection (a) for assessing a deficiency for that prior year is extended to include the period in subsection (h) or (j), whichever applies. But the amount assessable only because of this subsection cannot exceed the amount applied, credited, or refunded under section 6411, minus any amount assessable only because of subsection (h) or (j), as applicable. (l) Special rule for chapter 42 and similar taxes. (1) In general. For a tax under section 4912, under chapter 42 other than section 4940, or under section 4975, the “return” referred to in this section is the return filed by the private foundation, plan, trust, or other organization, as applicable, for the year when the act or failure to act creating the tax liability occurred. For section 4940, it is the private foundation’s return for the taxable year for which the tax is imposed. (2) Certain contributions to section 501(c)(3) organizations. If a private foundation’s tax deficiency results from its failure to qualify a contribution under section 4942(g)(3) because a section 501(c)(3) organization failed to make the distribution required by section 4942(g)(3), the deficiency may be assessed before 1 year after the assessment period ends for a deficiency for the taxable year to which the contribution relates. (3) Certain set-asides described in section 4942(g)(2). If a deficiency results because an amount set aside by a private foundation for a specific project fails to be treated as a qualifying distribution under section 4942(g)(2)(B)(ii), the deficiency may be assessed before 2 years after the assessment period ends for a deficiency for the taxable year to which the set-aside relates. (4) Individual retirement plans. (A) In general. For a tax under section 4973 or 4974 connected with an individual retirement plan, the “return” referred to in this section includes the income-tax return filed by the person subject to that tax for the year when the act or failure to act creating the liability occurred. (B) Rule in case of individuals not required to file return. If that person was not required to file an income-tax return for that year—(i) the return referred to in this section is the income-tax return the person would have been required to file if the person had been required to file one; and (ii) the 3-year period in subsection (a) is treated as beginning on the date that return would have been due, without counting any extension. (C) Period for assessment in case of income tax return. If the return for a section 4973 tax is the individual’s income-tax return for this section, subsection (a) applies a 6-year period instead of 3 years. (D) Exception for certain acquisitions of property. For a section 4973 tax attributable to acquiring property for less than fair market value, subparagraph (A) does not apply. (m) Deficiencies attributable to election of certain credits. The assessment period for a deficiency attributable to an election, or revocation of an election, under section 30B(h)(9), 30C(e)(4), 30D(f)(6), 35(g)(11), 40(f), 43, 45B, 45C(d)(4), 45H(g), or 51(j) cannot end before 1 year after the Secretary is notified of the election or revocation. (n) Assessable payment of employer shared responsibility. For an assessable payment under section 4980H, the assessment period ends at the end of 6 years beginning on the due date for the section 6056 return for the relevant calendar year, or, if later, on the date that return was filed. (o) Material assistance from a prohibited foreign entity. A deficiency caused by an error concerning the determination under section 7701(a)(52) for a taxable year may be assessed within 6 years after the return for that year was filed. (p) Cross reference. For the assessment-and-collection limitation period when a joint income-tax return is filed after separate returns were filed, see section 6013(b)(3) and (4).