(a) In general—(1) General rule. In the case of any plan (as defined in paragraph (b)(3) of this section), there is imposed a tax for the employer's taxable year equal to 10 percent of the sum of:

(i) Any excess contributions under a plan for the plan year ending in the taxable year; and

(ii) Any excess aggregate contributions under the plan for the plan year ending in the taxable year.

(2) Liability for tax. The tax imposed by paragraph (a)(1) of this section is to be paid by the employer. In the case of a collectively bargained plan to which section 413(b) applies, all employers who are parties to the collective bargaining agreement and whose employees are participants in the plan are jointly and severally liable for the tax.

(3) Due date and form for payment of tax—(i) The tax described in paragraph (a)(1) of this section is due on the last day of the 15th month after the close of the plan year to which the excess contributions or excess aggregate contributions relate.

(ii) An employer that owes the tax described in paragraph (a)(1) of this section must file the form prescribed by the Commissioner for the payment of the tax.

(4) Special rule for simplified employee pensions—(i) An employer that maintains a simplified employee pension (SEP) as defined in section 408(k) that accepts elective contributions is exempted from the tax of section 4979 and paragraph (a)(1) of this section if it notifies its employees of the fact and tax consequences of excess contributions within 21⁄2 months following the plan year for which excess contributions are made. The notification must meet the standards of paragraph (a)(4)(ii) of this section.

(ii) The employer's notification to each affected employee of the excess SEP contributions must specifically state, in a manner calculated to be understood by the average plan participant: the amount of the excess contributions attributable to that employee's elective deferrals; the calendar year for which the excess contributions were made; that the excess contributions are includible in the affected employee's gross income for the specified calendar year; and that failure to withdraw the excess contributions and income attributable thereto by the due date (plus extensions) for filing the affected employee's tax return for the preceding calendar year may result in significant penalties.

(iii) If an employer does not notify its employees by the last day of the 12-month period following the year of excess SEP contributions, the SEP will no longer be considered to meet the requirements of section 408(k)(6).

(b) Definitions. The following is a list of terms and definitions to be used for purposes of section 4979 and this section:

(1) Excess aggregate contributions. The term “excess aggregate contribution” has the meaning set forth in §1.401(m)-5 of this chapter. For purposes of determining excess aggregate contributions under an annuity contract described in section 403(b), the contract is treated as a plan described in section 401(a).

(2) Excess contributions. The term “excess contributions” has the meaning set forth in sections 401(k)(8)(B), 408(k)(6)(C)(ii), and 501(c)(18). See, e.g., §1.401(k)-6 of this chapter.

(3) Plan. The term “plan” means:

(i) A plan described in section 401(a) that includes a trust exempt from tax under section 501(a);

(ii) Any annuity plan described in section 403(a);

(iii) Any annuity contract described in section 403(b);

(iv) A simplified employee pension of an employer that satisfies the requirements of section 408(k); and

(v) A plan described in section 501(c)(18).

The term includes any plan that at any time has been determined by the Secretary to be one of the types of plans described in this paragraph (b)(3).

(c) No tax when excess distributed within 21⁄2 months of close of year or additional employer contributions made—(1) General rule. No tax is imposed under this section on any excess contribution or excess aggregate contribution, as the case may be, to the extent the contribution (together with any income allocable thereto) is corrected before the close of the first 21⁄2 months of the following plan year (6 months in the case of a plan that includes an eligible automatic contribution arrangement within the meaning of section 414(w)). The extension to 6 months applies to a distribution of excess contributions or excess aggregate contributions for a plan year beginning on or after January 1, 2010, only where all the eligible NHCEs and eligible HCEs (both as defined in §1.401(k)-6 of this Chapter) are covered employees under an eligible automatic contribution arrangement within the meaning of section 414(w) for the entire plan year (or the portion of the plan year that the eligible NHCEs and eligible HCEs are eligible employees under the plan)). Qualified nonelective contributions and qualified matching contributions taken into account under §1.401(k)-2(a)(6) of this Chapter or qualified nonelective contributions or elective contributions taken into account under §1.401(m)-2(a)(6) of this Chapter for a plan year may permit a plan to avoid excess contributions or excess aggregate contributions, respectively, even if made after the close of the 21⁄2 month (or 6 month) period for distributing excess contributions or excess aggregate contributions without the excise tax. See §1.401(k)-2(b)(1)(i) and (5)(i) of this Chapter for methods to avoid excess contributions, and §1.401(m)-2(b)(1)(i) of the Chapter for methods to avoid excess aggregate contributions.

(2) Tax treatment of distributions. See §1.401(k)-2(b)(3)(ii) and (2)(vi) of this chapter for rules for determining the tax consequences to a participant of a distribution or recharacterization of excess contributions and income allocable thereto, including a special rule for de minimis distributions. See §1.401(m)-2(b)(2)(vi) of this chapter for rules for determining the tax consequences to a participant of a distribution of excess aggregate contributions and income allocable thereto.

(3) Income. See §1.401(k)-2(b)(2)(iv) of this chapter for rules for determining income allocable to excess contributions. See §1.401(m)-2(b)(2)(iv) of this chapter for rules for determining income allocable to excess aggregate contributions.

(4) Example. The provisions of this paragraph (c) are illustrated by the following example.

(d) Effective date—(1) General rule. Except as provided in paragraphs (d)(2) through (4), this section is effective for plan years beginning after December 31, 1986.

(2) Section 403(b) annuity contracts. In the case of an annuity contract under section 403(b), this section applies to plan years beginning after December 31, 1988.

(3) Collectively bargained plans and plans of state or local governments. For plan years beginning before January 1, 1993, the provisions of this section do not apply to a collectively bargained plan that automatically satisfies the requirements of section 410(b). See §§1.401(a)(4)-1(c)(5) and 1.410(b)-2(b)(7) of this chapter. In the case of a plan (including a collectively bargained plan) maintained by a state or local government, the provisions of this section do not apply for plan years beginning before the later of January 1, 1996, or 90 days after the opening of the first legislative session beginning on or after January 1, 1996, of the governing body with authority to amend the plan, if that body does not meet continuously. For purposes of this paragraph (d)(3), the term governing body with authority to amend the plan means the legislature, board, commission, council, or other governing body with authority to amend the plan.

(4) Plan years beginning before January 1, 1992. For plan years beginning before January 1, 1992, a reasonable interpretation of the rules set forth in section 4979, as in effect during those years, may be relied upon in determining whether the excise tax is due for those years.

[T.D. 8357, 56 FR 40550, Aug. 15, 1991, as amended by T.D. 8581, 59 FR 66181, Dec. 23, 1994; T.D. 9169, 69 FR 78153, Dec. 29, 2004; T.D. 9447, 74 FR 8214, Feb. 24, 2009]