(a) Purpose of this section. This section provides rules for determining the deductible limit under section 404(a)(1)(A) of the Internal Revenue Code of 1954 for defined benefit plans.

(b) Definitions. For purposes of this section—

(1) Section 404(a). The term “old section 404(a)” means section 404(a) as in effect on September 1, 1974. Any reference to section 404 without the designation “old” is a reference to section 404 as amended by the Employee Retirement Income Security Act of 1974.

(2) Ten-year amortization base. The term “10-year amortization base” means either the past service and other supplementary pension and annuity credits described in section 404(a)(1)(A)(iii) or any base established in accordance with paragraph (g) of this section. A plan may have several 10-year amortization bases to reflect different plan amendments, changes in actuarial assumptions, changes in funding method, and experience gains and losses of previous years.

(3) Limit adjustment. The term “limit adjustment” with respect to any 10-year amortization base is the lesser of—

(i) The level annual amount necessary to amortize the base over 10 years using the valuation rate, or

(ii) The unamortized balance of the base,

(4) Absolute value. The term “absolute value” for any number is the value of that number, treating negative numbers as if they were positive numbers. For example, the absolute value of 5 is 5 and the absolute value of minus 3 is 3. On the other hand, the true value of minus 3 is minus 3. This term is relevant to the computation of the limit adjustment described in paragraph (b)(3) and the remaining amortization period of combined bases described in paragraph (i)(3) of this section.

(5) Valuation rate. The term “valuation rate” means the assumed interest rate used to value plan liabilities.

(c) Use of plan in determining deductible limit for employer's taxable year. Although the deductible limit applies for an employer's taxable year, the deductible limit is determined on the basis of a plan year. If the employer's taxable year coincides with the plan year, the deductible limit for the taxable year is the deductible limit for the plan year that coincides with that year. If the employer's taxable year does not coincide with the plan year, the deductible limit under section 404(a)(1)(A) (i), (ii), or (iii) for a given taxable year of the employer is one of the following alternatives:

(1) The deductible limit determined for the plan year commencing within the taxable year.

(2) The deductible limit determined for the plan year ending within the taxable year, or

(3) A weighted average of alternatives (1) and (2). Such an average may be based, for example, upon the number of months of each plan year falling within the taxable year.

(d) Computation of deductible limit for a plan year—(1) General rules. The computation of the deductible limit for a plan year is based on the funding methods, actuarial assumptions, and benefit structure used for purposes of section 412, determined without regard to section 412(g) (relating to the alternative minimum funding standard), for the plan year. The method of valuing assets for purposes of section 404 must be the same method of valuing assets used for purposes of section 412.

(2) Special adjustments of computations under section 412. To apply the rules of this section (i.e., rules regarding the computation of normal cost with aggregate type funding methods, unfunded liabilities, and the full funding limitation described in paragraph (k) of the section, where applicable) with respect to a given plan year in computing deductible limits under section 404 (a)(1)(A), the following adjustments must be made:

(i) There must be excluded from the total assets of the plan the amount of any plan contribution for a plan year for which the plan was qualified under section 401(a), 403(a) or 405(a) that has not been previously deducted, even though that amount may have been credited to the funding standard account under section 412(b)(3). In the case of a plan using a spread gain funding method which maintains an unfunded liability (e.g., the frozen initial liability method, but not the aggregate method), the amount described in the preceding sentence must be included in the unfunded liability of the plan.

(ii) There must be included in the total assets of the plan for a plan year the amount of any plan contribution that has been deducted with respect to a prior plan year, even though that amount is considered under section 412 to be contributed in a plan year subsequent to that prior plan year. In the case of a plan using a spread gain funding method which does not maintain an unfunded liability, the amount described in the preceding sentence must be excluded from the unfunded liability of the plan.

(e) Special computation rules under section 404(a)(1)(A)(i)—(1) In general. For purposes of determining the deductible limit under section 404(a)(1)(A)(i), the deductible limit with respect to a plan year is the sum of—

(i) The amount required to satisfy the minimum funding standard of section 412(a) (determined without regard to section 412(g)) for the plan year and

(ii) An amount equal to the includible employer contributions. The term “includible employer contributions” means employer contributions which were required by section 412 for the plan year immediately preceding such plan year, and which were not deductible under section 404(a) for the prior taxable year of the employer solely because they were not contributed during the prior taxable year (determine with regard to section 404(a)(6)).

(2) Rule for an employer using alternative minimum funding standard account and computing its deduction under section 404(a)(1)(A)(i). This paragraph (e)(2) applies if the minimum funding requirements for the plan are determined under the alternative minimum funding standard described in section 412(g) for both the current plan year and the immediately preceding plan year. In that case, the deductible limit under section 404(a)(1)(A)(i) (regarding the minimum funding requirement of section 412) for the current year is the sum of the amount determined under the rules of paragraph (e)(1) of this section.

(i) Plus the charge under section 412(b)(2)(D), and

(ii) Less the credit under section 412(b)(3)(D),

(f) Special computation rules under section 404(a)(1)(A) (ii) and (iii)—(1) In general. Subject to the full funding limitation described in paragraph (k) of this section, the deductible limit under section 404(a)(1)(A)(ii) and (iii) is the normal cost of the plan (determined in accordance with paragraph (d) of this section).

(2) Adjustments in calculating limit under section 404 (a)(1)(A)(iii). In calculating the deductible limit under section 404(a)(1)(A)(iii), the normal cost of the plan is—

(i) Decreased by the limit adjustments to any unamortized bases required by paragraph (g) of this section, for example, bases that are due to a net experience gain, a change in actuarial assumptions, a change in funding method, or a plan provision or amendment which decreases the accrued liability of the plan, and

(ii) Increased by the limit adjustments of any unamortized 10-year amortization bases required by paragraph (g) or (j) of this section, for example, bases that are due to a net experience loss, a change in actuarial assumptions, a change in funding method, or a plan provision or amendment which increases the accrued liability.

(3) Timing for computations and interest adjustments under section 404(a)(1)(A) (ii) and (iii). Regardless of the actual time when contributions are made to a plan, in computing the deductible limit under section 404(a)(1)(A) (ii) and (iii) the normal cost and limit adjustments shall be computed as of the date when contributions are assumed to be made (“the computation date”) and adjusted for interest at the valuation rate from the computation date to the earlier of—

(i) The last day of the plan year used to compute the deductible limit for the taxable year, or

(ii) The last day of that taxable year. For additional provisions relating to the timing of computations and interest adjustments, see paragraph (h)(6) of this section (relating to the timing of computations and interest adjustments in the maintenance of 10-year amortization bases). For taxable years beginning before April 22, 1981, computations under the preceding sentence may, as an alternative, be based on prior published positions of the Internal Revenue Service under section 404(a).

(4) Special limit under section 404(a)(1)(A)(ii). If the deduction for the plan year is determined solely on the basis of section 404(a)(1)(A)(ii) (that is, without regard to clauses (i) or (iii)), the special limitation contained in section 404(a)(1)(A)(ii), regarding the unfunded cost with respect to any three individuals, applies, notwithstanding the rules contained in paragraphs (d)(2) and (f)(1) of this section.

(g) Establishment of a 10-year amortization base—(1) Experience gains and losses. In the case of a plan valued by the use of a funding method which is an immediate gain type of funding method (and therefore separately amortizes rather than includes experience gains and losses as a part of the normal cost of the plan), a 10-year amortization base must be established in any plan year equal to the net experience gain or loss required under section 412 to be determined with respect to that plan year. The base is to be maintained in accordance with paragraph (h) of this section. Such a base must not be established if the deductible limit is determined by use of a funding method which is a spread gain type of funding method (under which experience gains and losses are spread over future periods as a part of the plan's normal cost). Examples of the immediate gain type of funding method are the unit credit method, entry age normal cost method, and the individual level premium cost method. Examples of the spread gain type of funding method are the aggregate cost method, frozen initial liability cost method, and the attained age normal cost method.

(2) Change in actuarial assumptions. (i) If the creation of an amortization base is required under the rules of section 412(b) (2)(B)(v) or (3)(B)(iii) (as applied to the funding method used by the plan), a 10-year amortization base must be established at the time of a change in actuarial assumptions used to value plan liabilities. The amount of the base is the difference between the accrued liability calculated on the basis of the new assumptions and the accrued liability calculated on the basis of the old assumptions. Both computations of accrued liability are made as of the date of the change in assumptions.

(ii) A plan using a funding method of the spread gain type does not directly determine an accrued liability. If a plan using such a method is required under section 412(b) (2)(B)(v) or (3)(B)(iii) to create an amortization base, it must establish a base as described in paragraph (g)(2)(i) of this section for a change in actuarial assumptions by determining an accrued liability on the basis of another funding method (of the immediate gain type) that does determine an accrued liability. (The aggregate method is an example of a funding method that is not required under section 412(b) (2)(B)(v) or (3)(B)(iii) to create an amortization base.) The funding method chosen to determine the accrued liability of the plan in these cases must be the same method used to establish all other 10-year amortization bases maintained by the plan, if any. These bases must be maintained in accordance with paragraph (h) of this section.

(3) Past service or supplemental credits. A 10-year base must be established when a plan is established or amended, if the creation of an amortizable base is required under the rules of section 412(b)(2)(B) (ii) or (iii), or (b)(3)(B)(i) (as applied to the funding method used by the plan). The amount of the base is the accrued liability arising from, or the decrease in accrued liability resulting from, the establishment or amendment of the plan. The base must be maintained in accordance with paragraph (h) of this section.

(4) Change in funding method. If a change in funding method results in an increase or decrease in an unfunded liability required to be amortized under section 412, a 10-year base must be established equal to the increase or decrease in unfunded liability resulting from the change in funding method. The base must be maintained in accordance with paragraph (h) of this section.

(h) Maintenance of 10-year amortization base—(1) In general. Each time a 10-year amortization base is established, whether by a change in funding method, by plan amendment, by change in actuarial assumptions, or by experience gains and losses, the base must, except as provided in paragraph (i) of this section, be separately maintained in order to determine when the unamortized amount of the base is zero. The sum of the unamortized balances of all of the 10-year bases must equal the plan's unfunded liability with the adjustments described in paragraph (d) of this section, if applicable. When the unamortized amount of a base is zero, the deductible limit is no longer adjusted to reflect the amortization of the base.

(2) First year's base. See either paragraph (g) or paragraph (i) of this section for rules applicable with respect to the first year of a base.

(3) Succeeding year's base. For any plan year after the first year of a base, the unamortized amount of the base is equal to—

(i) The unamortized amount of the base as of the valuation date in the prior plan year, plus

(ii) Interest at the valuation rate from the valuation date in the prior plan year to the valuation date in the current plan year on the amount described in subdivision (i), minus

(iii) The contribution described in paragraph (h)(4) of this section with respect to the base for the prior plan year.

(4) Contribution allocation with respect to each base. A portion of the total contribution for the prior plan year is allocated to each base. Generally, this portion equals the product of—

(i) The total contribution described in paragraph (h)(6) of this section with respect to all bases, and

(ii) The ratio of the amount described in paragraph (b)(3)(i) of this section with respect to the base to the sum (using true rather than absolute values) of such amounts with respect to all remaining bases.

(5) Other allocation methods. The Commissioner may authorize the use of methods other than the method described in paragraph (h)(4) of this section for allocating contributions to bases.

(6) Total contribution for all bases. The contribution with respect to all bases for the prior plan year (see paragraph (h)(3)(iii) of this section) is the difference between—

(i) The sum of (A) the total deduction (including a carryover deduction) for the prior year, (B) interest on the actual contributions for the prior year (whether or not deductible) at the valuation rate for the period between the dates as of which the contributions are credited under section 412 and the valuation date in the current plan year, and (C) interest on the carryover described in section 404(a)(1)(D) that is available at the beginning of the prior taxable year at the valuation rate for the period between the current and prior valuation dates, and

(ii) The normal cost for the prior plan year and interest on it at the valuation rate from the date as of which the normal cost is calculated to the current valuation date.

(7) Effect of failure to contribute normal cost plus interest on unamortized amounts. The failure to make a contribution at least equal to the sum of the normal cost plus interest on the unamortized amounts has the following effects under the preceding rules of this section—

(i) It does not create a new base.

(ii) It results in an increase in the unamortized amount of each base and consequently extends the time before the base is fully amortized.

(iii) The limit adjustment for any base is not increased (in absolute terms) even if the unamortized amount computed under paragraph (h) of this section exceeds the initial 10-year amortization base. Thus, if the total unamortized amount of the plan's bases at the beginning of the plan year is $100,000 (which is also the unfunded liability of the plan), and a required $50,000 normal cost contribution is not made for the plan year, the following effects occur. The total unamortized balance of the plan's bases increases by the $50,000 normal cost for the year (adjusted for interest), plus interest on the $100,000 balance of the bases; and, because of that increase, it will take a longer period to amortize the remaining balance of the bases. (The annual amortization amount does not change.)

(8) Required adjustment to a 10-year base limit adjustment if valuation rate changed. If there is a change in the valuation rate, the limit adjustment for all unamortized 10-year amortization bases must be changed, in addition to establishing a new base as provided in paragraph (g)(2) of this section. The new limit adjustment for any base is the level amount necessary to amortize the unamortized amount of the base over the remaining amortization period using the new valuation rate. The remaining amortization period of the base is the number of years at the end of which the unamortized amount of the base would be zero if the contribution made with respect to that base equaled the limit adjustment each year. This calculation of the remaining period is made on the basis of the valuation rate used before the change. Both the remaining amortization period and the revised limit adjustment may be determined through the use of standard annuity tables. The remaining period may be computed in terms of fractional years, or it may be rounded off to a full year. The unamortized amount of the base as of the valuation date and the remaining amortization period of that base shall not be changed by any change in the valuation rate.

(i) Combining bases—(1) General method. For purposes of section 404 only, and not for purposes of section 412, different 10-year amortization bases may be combined into a single 10-year amortization base if such single base satisfies all of the requirements of paragraph (i) (2), (3), and (4) of this section at the time of the combining of the different bases.

(2) Unamortized amount. The unamortized amount of the single base equals the sum, as of the date the combination is made, of the unamortized amount of the bases being combined (treating negative bases as having negative unamortized amounts).

(3) Remaining amortization period. The remaining amortization period of the single base is equal to (i) the sum of the separate products of (A) the unamortized amount of each of these bases (using absolute values) and (B) its remaining amortization period, divided by (ii) the sum of the unamortized amounts of each of the bases (using absolute values). For purposes of this paragraph (i)(3), the remaining amortization period of each base being combined is that number of years at the end of which the unamortized amount of the base would be zero if the contribution made with respect to that base equaled the limit adjustment of that base in each year. This number may be determined through the use of standard annuity tables. The remaining amortization period described in this paragraph may be computed in terms of fractional years, or it may be rounded off to a whole year.

(4) Limit adjustment. The limit adjustment for the single base is the level amount necessary to amortize the unamortized amount of the combined base over the remaining amortization period described in paragraph (i)(3) of this section, using the valuation rate. This amount may be determined through the use of standard annuity tables.

(5) Fresh start alternative. In lieu of combining different 10-year amortization bases, a plan may replace all existing bases with one new 10-year amortization base equal to the unfunded liability of the plan as of the time the new base is being established. This unfunded liability must be determined in accordance with the general rules of paragraphs (d) and (f) of this section. The unamortized amount of the base and the limit adjustment for the base will be determined as though the base were newly established.

(j) Initial 10-year amortization base for existing plan—(1) In general. In the case of a plan in existence before the effective date of section 404(a), the 10-year amortization base on the effective date of section 404(a) is the sum of all 10 percent bases existing immediately before section 404(a) became effective for the plan, determined under the rules of old section 404(a).

(2) Limit adjustment. The limit adjustment for the initial base is the lesser of the unamortized amount of such base or the sum of the amounts determined under paragraph (b)(3) of this section using the original balances of the remaining bases (under old section 404(a) rules) as the amount to be amortized.

(3) Unamortized amount. The employer may choose either to establish a single initial base reflecting both all prior 10-percent bases and the experience gain or loss for the immediately preceding actuarial period, or to establish a separate base for the prior 10-percent bases and another for the experience gain or loss for the immediately preceding period. If the initial 10-year amortization base reflects the net experience gain or loss from the immediately preceding actuarial period, the unamortized amount of the initial base shall equal the total unfunded liability on the effective date of section 404(a) determined in accordance with the general rules of paragraphs (d) and (f) of this section. If, however, a separate base will be used to reflect that gain or loss, the unamortized amount of the initial base shall equal such unfunded liability on the effective date of section 404(a), reduced by the net experience loss or increased by the net experience gain for the immediately preceding actuarial period. In this case, a separate 10-year amortization base must be established on the effective date equal to the net experience gain or loss. Thus, if the effective date unfunded liability is $100,000 and an experience loss of $15,000 is recognized on that date, and if the loss is to be treated as a separate base, the unamortized balances of the two bases would be $85,000 and $15,000. If the unfunded liability were the same $100,000, but a gain of $15,000 instead of a loss were recognized on that date, the unamortized balances of the two bases would be $115,000 and a credit base of $15,000. In both cases, if only one 10-year base is to be established on the effective date, its unamortized balance would be $100,000 (the unfunded liability of the plan). See paragraphs (d) and (f) for rules for determining the unfunded liability of the plan.

(k) Effect of full funding limit on 10-year-amortization bases. The amount deductible under section 404(a)(1)(A) (i), (ii), or (iii) for a plan year may not exceed the full funding limitation for that year. See section 412 and paragraphs (d), (e), and (f) of this section for rules to be used in the computation of the full funding limitation. If the total deductible contribution (including carryover) for a plan year equals or exceeds the full funding limitation for the year, all 10-year amortization bases maintained by the plan will be considered fully amortized, and the deductible limit for subsequent plan years will not be adjusted to reflect the amortization of these bases.

(l) Transitional rules—(1) Plan years beginning before April 22, 1981. In determining the deductible limit for plan years beginning before April 22, 1981, a contribution will be deductible under section 404(a)(1)(A) if the computation of the deductible limit is based on an interpretation of section 404(a)(1)(A) that is reasonable when considered with prior published positions of the Internal Revenue Service. A computation of the deductible limit may satisfy the preceding sentence even if it does not satisfy the rules contained in paragraphs (c) through (i) of this section.

(2) Transitional approaches. The deductible limit determined for the first plan year with respect to which a plan applies the rules contained in paragraphs (c) through (i) of this section must be computed using one of the following approaches—

(i) The plan (whether or not in existence before the effective date of section 404(a)) may apply the rules of paragraph (j) for establishing the initial base for an existing plan, treating 10-year bases (if any) as 10 percent bases in adding bases.

(ii) The plan may apply the fresh start alternative for combining bases under paragraph (i)(5).

(iii) The plan may retroactively establish 10-year amortization bases for years with respect to which section 404(a)(1)(A) and the rules of this section would have applied but for the transition rule contained in paragraph (l)(1) of this section. Contributions actually deducted are used in retroactively establishing and maintaining these bases under paragraph (h). However, a deduction already taken shall not be recomputed because of the retroactive establishment of a base.

(m) Effective date of section 404(a). In the case of a plan which was in existence on January 1, 1974, section 404(a) generally applies for contributions on account of taxable years of an employer ending with or within plan years beginning after December 31, 1974. In the case of a plan not in existence on January 1, 1974, section 404(a) generally applies for contributions on account of taxable years of an employer ending with or within plan years beginning after September 4, 1974. See § 1.410(a)-2(c) for rules concerning the time of plan existence. See also § 1.410(a)-2(d), which provides that a plan in existence on January 1, 1974, may elect to have certain provisions, including the amendments to section 404(a) contained in section 1013 of the Employee Retirement Income Security Act of 1974, apply to a plan year beginning after September 2, 1974, and before the otherwise applicable effective date contained in that section.