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26 CFR §54.4971(c)-1 — (c)-1 Taxes on failure to meet minimum funding standards; definitions.

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
  1. (a)In general. This section sets forth definitions that apply for purposes of applying the rules of section 4971.
  2. (b)Accumulated funding deficiency
    1. (1)Multiemployer plans. With respect to a multiemployer plan defined in section 414(f), the term accumulated funding deficiency has the meaning given to that term by section 431. A plan's accumulated funding deficiency for a plan year takes into account all charges and credits to the funding standard account under section 412 for plan years before the first plan year for which section 431 applies to the plan.
    2. (2)CSEC plans. With respect to a CSEC plan (that is, a plan that fits within the definition of a CSEC plan in section 414(y) for plan years beginning on or after January 1, 2014 and for which the election under section 414(y)(3)(A) has not been made), the term accumulated funding deficiency means the CSEC accumulated funding deficiency determined under section 433. A plan's CSEC accumulated funding deficiency for a plan year takes into account all charges and credits to the funding standard account under section 412 for plan years before the first plan year for which section 433 applies to the plan.
  3. (c)Unpaid minimum required contribution
    1. (1)In general. The term unpaid minimum required contribution means, with respect to any plan year, the portion of the minimum required contribution under section 430 for the plan year for which contributions have not been made on or before the due date for the plan year under section 430(j)(1). The unpaid minimum required contribution is determined after taking into account the interest adjustment to contributions under § 1.430(j)-1(b)(4) and any offsets from use of the funding balances under § 1.430(f)-1(d).
    2. (2)Accumulated funding deficiency for pre-effective plan year. For purposes of this section, a plan's accumulated funding deficiency under section 412 for the pre-effective plan year is treated as an unpaid minimum required contribution for that plan year until correction is made under the rules of paragraph (d)(2) of this section.
  4. (d)Correct
    1. (1)Accumulated funding deficiency. With respect to an accumulated funding deficiency for a plan year that is described in paragraph (b) of this section, the term correct means to contribute, to or under the plan, the amount necessary to reduce the accumulated funding deficiency as of the end of that plan year to zero. To reduce the deficiency to zero, the contribution must include interest at the plan's valuation interest rate for the period between the end of that plan year and the date of the contribution (determined taking into account the rules of section 431(c)(8) or section 433(c)(9), as applicable).
    2. (2)Unpaid minimum required contribution
      1. (i)In general. With respect to an unpaid minimum required contribution for a plan year, the term correct means to contribute, to or under the plan, an amount that, when discounted to the valuation date for the plan year for which the unpaid minimum required contribution is due at the appropriate rate of interest, equals or exceeds the unpaid minimum required contribution. For this purpose, the appropriate rate of interest is the plan's effective interest rate for the plan year for which the unpaid minimum required contribution is due except to the extent that the payments are subject to additional interest as provided under section 430(j)(3) or (4).
      2. (ii)Pre-PPA accumulated funding deficiency. With respect to the accumulated funding deficiency under section 412 for the pre-effective plan year that is described in paragraph (c)(2) of this section, the term correct means to contribute, to or under the plan, the amount of that accumulated funding deficiency increased with interest from the end of the pre-effective plan year to the date of the contribution at the plan's valuation interest rate for the pre-effective plan year.
      3. (iii)Ordering rule. For purposes of section 4971 and this section, a contribution is attributable first to the earliest plan year of any unpaid minimum required contribution for which correction has not yet been made.
    3. (3)Corrective action of certain retroactive plan amendments. Certain retroactive plan amendments that meet the requirements of section 412(d)(2) may reduce the minimum required contribution for a plan year, which would reduce the accumulated funding deficiency or the amount of the unpaid minimum required contribution for a plan year.
  5. (e)Taxable period
    1. (1)In general. The term taxable period means the period beginning with the end of the plan year in which there is an accumulated funding deficiency or unpaid minimum required contribution, whichever is applicable, and ending on the earlier of:
      1. (i)The date of mailing of a notice of deficiency under section 6212 with respect to the tax imposed by section 4971(a); or
      2. (ii)The date on which the tax imposed by section 4971(a) is assessed.
    2. (2)Special rule. Where a notice of deficiency referred to in paragraph (e)(1)(i) of this section is not mailed because a waiver of the restrictions on assessment and collection of a deficiency has been accepted or because the deficiency is paid, the date of filing of the waiver or the date of such payment, respectively, is treated as the end of the taxable period.
  6. (f)Single-employer plan. The term single-employer plan means a plan to which the minimum funding requirements of section 412 apply that is not a multiemployer plan as described in section 414(f). The term single-employer plan includes a multiple employer plan to which section 413(c) applies, other than a CSEC plan as described in paragraph (b)(2) of this section.
  7. (g)Examples. The following examples illustrate the rules of this section.
  8. (h)Effective/applicability dates and transition rules
    1. (1)Statutory effective date
      1. (i)In general. In general, the amendments made to section 4971 by section 114 of the Pension Protection Act of 2006, Public Law 109-280, 120 Stat. 780 (2006), as amended (PPA '06), apply to taxable years beginning on or after January 1, 2008, but only with respect to a plan year that—
        1. (A)Begins on or after January 1, 2008; and
        2. (B)Ends with or within any such taxable year.
      2. (ii)Plans with delayed PPA '06 effective dates. In the case of a plan for which the effective date of section 430 for purposes of determining the minimum required contribution is delayed in accordance with sections 104 through 106 of PPA '06, the amendments made to section 4971 by section 114 of PPA '06 apply to taxable years beginning on or after January 1, 2008, but only with respect to a plan year—
        1. (A)To which section 430 applies to determine the minimum required contribution of the plan; and
        2. (B)That ends with or within any such taxable year.
    2. (2)Effective date of regulations. This section is effective for taxable years beginning on or after the statutory effective date described in paragraph (h)(1) of this section, but in no event does this section apply to taxable years ending before April 15, 2008.
    3. (3)Pre-effective plan year. For purposes of this section, the pre-effective plan year for a plan is the plan year described in § 1.430(a)-1(h)(5) of this chapter. Thus, except for plans with a delayed effective date under paragraph (h)(1)(ii) of this section, the pre-effective plan year for a plan is the last plan year beginning before January 1, 2008.