---
kind: "section"
citation: "26 U.S.C. § 6663"
title: "26"
title_heading: "Internal Revenue Code"
number: "6663"
heading: "Imposition of fraud penalty"
release: "119-102"
date: "2026-07-12"
url: "https://uscodex.org/usc/26/6663"
units:
  - "Subtitle F — Procedure and Administration"
  - "Chapter 68 — Additions to the Tax, Additional Amounts, and Assessable Penalties"
  - "Subchapter A — Additions to the Tax and Additional Amounts"
  - "Part II — Accuracy-Related and Fraud Penalties"
---

# §6663. Imposition of fraud penalty

- (a) **Imposition of penalty—** If any part of any [underpayment](/usc/26/6664.md?p=a) of tax required to be shown on a return is due to fraud, there shall be added to the tax an amount equal to 75 percent of the portion of the [underpayment](/usc/26/6664.md?p=a) which is attributable to fraud.
- (b) **Determination of portion attributable to fraud—** If the [Secretary](/usc/26/7701.md?p=a-11-B) establishes that any portion of an [underpayment](/usc/26/6664.md?p=a) is attributable to fraud, the entire [underpayment](/usc/26/6664.md?p=a) shall be treated as attributable to fraud, except with respect to any portion of the [underpayment](/usc/26/6664.md?p=a) which the [taxpayer](/usc/26/7701.md?p=a-14) establishes (by a preponderance of the evidence) is not attributable to fraud.
- (c) **Special rule for joint returns—** In the case of a [joint return](/usc/26/7701.md?p=a-38), this section shall not apply with respect to a spouse unless some part of the [underpayment](/usc/26/6664.md?p=a) is due to the fraud of such spouse.

## Source credit

(Added Pub. L. 101–239, title VII, § 7721(a), Dec. 19, 1989, 103 Stat. 2397.)

## Notes

### Statutory Notes and Related Subsidiaries

### Effective Date

Section applicable to returns the due date for which (determined without regard to extensions) is after Dec. 31, 1989, see section 7721(d) of Pub. L. 101–239, set out as an Effective Date of 1989 Amendment note under section 461 of this title.