Treasury Regulations · 26 CFR
§ 1.6664-0. Table of contents.
Regulation text, no changes From the eCFR, current as of October 15, 2026. The eCFR is an authoritative but unofficial editorial compilation of the Code of Federal Regulations; the official text is the annual CFR on govinfo. Compare it with this section on ecfr.gov (external site) or the official annual CFR on govinfo (external site).
Regulation under 26 U.S.C. § 6664
Cite as 26 CFR § 1.6664-0
At a glance
Read from the text and its source citation. Not part of the regulation.
- Status
- In the current eCFR
- Issued
- December 31, 1991 by T.D. 8381
- Last amended
- January 9, 2007 by T.D. 9309
- Issued under
- 26 U.S.C. § 6664
- Length
- 415 words · about 2 min to read
- Cross-references
- cites 2 Code sections and 5 regulations; cited by 0
This section lists the captions in §§ 1.6664-1 through 1.6664-4T.
(a) In general.
(b) Effective date.
(1) In general.
(2) Reasonable cause and good faith exception to section 6662 penalties.
(i) For returns due after September 1, 1995.
(ii) For returns filed after December 31, 2002.
(3) Qualified amended returns.
§ 1.6664-2 Underpayment.(a) Underpayment defined.
(b) Amount of income tax imposed.
(c) Amount shown as the tax by the taxpayer on his return.
(1) Defined.
(2) Effect of qualified amended return.
(3) Qualified amended return defined.
(i) General rule.
(ii) Undisclosed listed transactions.
(4) Special rules.
(5) Examples.
(d) Amounts not so shown previously assessed (or collected without assessment).
(e) Rebates.
(f) Underpayments for certain carryback years not reduced by amount of carrybacks.
(g) Examples.
§ 1.6664-3 Ordering rules for determining the total amount of penalties imposed.(a) In general.
(b) Order in which adjustments are taken into account.
(c) Manner in which unclaimed prepayment credits are allocated.
(d) Examples.
§ 1.6664-4 Reasonable cause and good faith exception to section 6662 penalties.(a) In general.
(b) Facts and circumstances taken into account.
(1) In general.
(2) Examples.
(c) Reliance on opinion or advice.
(1) Fact and circumstances; minimum requirements.
(i) All facts and circumstances considered.
(ii) No unreasonable assumptions.
(iii) Reliance on the invalidity of a regulation.
(2) Advice defined.
(3) Cross-reference.
(d) Underpayments attributable to reportable transactions.
(e) Pass-through items.
(f) Special rules for substantial understatement penalty attributable to tax shelter items of corporations.
(1) In general; facts and circumstances.
(2) Reasonable cause based on legal justification.
(i) Minimum requirements.
(A) Authority requirement.
(B) Belief requirement.
(ii) Legal justification defined.
(3) Minimum requirements not dispositive.
(4) Other factors.
(g) Transactions between persons described in section 482 and net section 482 transfer price adjustments. [Reserved]
(h) Valuation misstatements of charitable deduction property.
(1) In general.
(2) Definitions.
(i) Charitable deduction property.
(ii) Qualified appraisal.
(iii) Qualified appraiser.
(3) Special rules.
§ 1.6664-4T Reasonable cause and good faith exception to section 6662 penalties(a)-(c) [Reserved]
(d) Transactions between persons described in section 482 and net section 482 transfer price adjustments.
[T.D. 8381, 56 FR 67505, Dec. 31, 1991, as amended by T.D. 8519, 59 FR 4799, Feb. 2, 1994; T.D. 8617, 60 FR 45666, Sept. 1, 1995; T.D. 8656, 61 FR 4885, Feb. 9, 1996; T.D. 8790, 63 FR 66435, Dec. 2, 1998; T.D. 9109, 68 FR 75128, Dec. 30, 2003; T.D. 9309, 72 FR 903, Jan. 9, 2007]
Cross-references
Computed from the citations in the text of 26 CFR.
Code sections it cites
- § 6662 Imposition of accuracy-related penalty on underpayments
- § 482 Allocation of income and deductions among taxpayers
Regulations it cites
- § 1.6664-1 Accuracy-related and fraud penalties; definitions, effective date and special rules.
- § 1.6664-2 Underpayment.
- § 1.6664-3 Ordering rules for determining the total amount of penalties imposed.
- § 1.6664-4 Reasonable cause and good faith exception to section 6662 penalties.
- § 1.6664-4T Reasonable cause and good faith exception to section 6662 penalties.
Amendment history
From the source citation at the end of the section, newest first. T.D. is a Treasury decision; FR is the Federal Register.
- Amended by T.D. 9309 (72 FR 903)
- Amended by T.D. 9109 (68 FR 75128)
- Amended by T.D. 8790 (63 FR 66435)
- Amended by T.D. 8656 (61 FR 4885)
- Amended by T.D. 8617 (60 FR 45666)
- Amended by T.D. 8519 (59 FR 4799)
- Issued by T.D. 8381 (56 FR 67505)
Where it sits in 26 CFR
- Subchapter A Income tax
- Part 1 Income taxes
- Additions to the tax, additional amounts, and assessable penalties
Nearby sections
- § 1.6662-5T Substantial and gross valuation misstatements under chapter 1 (temporary).
- § 1.6662-6 Transactions between persons described in section 482 and net section 482 transfer price adjustments.
- § 1.6662-7 Omnibus Budget Reconciliation Act of 1993 changes to the accuracy-related penalty.
- § 1.6662-9 Inconsistent estate basis reporting.
- § 1.6664-0 Table of contents.
- § 1.6664-1 Accuracy-related and fraud penalties; definitions, effective date and special rules.
- § 1.6664-2 Underpayment.
- § 1.6664-3 Ordering rules for determining the total amount of penalties imposed.
- § 1.6664-4 Reasonable cause and good faith exception to section 6662 penalties.