16.1 Actual Deferral Percentage (ADP) Test: Eligible Participants & Included Deferrals

16.1 Actual Deferral Percentage (ADP) Test: Eligible Participants & Included Deferrals

[!NOTE] The Statutory Gateway for Cash or Deferred Arrangements A qualified Cash or Deferred Arrangement (CODA) governed by IRC §401(k) allows employees to elect between receiving cash compensation currently or deferring that compensation into a tax-qualified retirement trust. Because higher-income executives naturally possess greater discretionary income to shelter from current taxation, Congress enacted IRC §401(k)(3) and the supporting regulations under Treas. Reg. §1.401(k)-1 and §1.401(k)-2 to prevent 401(k) plans from operating as tax shelters exclusively for management.

Unlike standard qualified plans that satisfy nondiscrimination under IRC §401(a)(4) based on employer contribution rates or actuarial benefit accruals, a 401(k) arrangement must satisfy the objective mathematical benchmarks of the Actual Deferral Percentage (ADP) Test on an annual basis (unless designed as a statutory safe harbor plan). Understanding how to identify the eligible testing universe, calculate individual deferral rates, and compute group averages is foundational for every retirement plan professional preparing for the ASPPA QKA credential.

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Statutory Architecture of the ADP Test: IRC §401(k)(3)

Under IRC §401(k)(3)(A), a cash or deferred arrangement is treated as nondiscriminatory under IRC §401(a)(4) for a plan year if and only if the Actual Deferral Percentage for the group of eligible Highly Compensated Employees (HCEs) bears a relationship to the ADP for the group of eligible Non-Highly Compensated Employees (NHCEs) that satisfies one of two statutory mathematical standards (the 1.25 Test or the 2.0 / 2-Percentage-Point Spread Test, examined in detail in Section 16.3).

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|                         THE THREE-STAGE ARCHITECTURE OF ADP TESTING                               |
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|                                                                                                   |
|   STAGE 1: IDENTIFY THE TESTING UNIVERSE (Treas. Reg. §1.401(k)-6)                                |
|   • Determine all employees eligible to make elective deferrals at ANY TIME during the plan year. |
|   • Segregate eligible employees into HCEs and NHCEs under IRC §414(q).                           |
|   • Include zero-deferrers, suspended employees, and mid-year terminations.                       |
|                                                                                                   |
|   STAGE 2: CALCULATE INDIVIDUAL ACTUAL DEFERRAL RATIOS (ADRs)                                     |
|   • For each eligible employee:                                                                   |
|                                                                                                   |
|                   Includible Elective Deferrals (Pre-Tax + Roth, Capped)                          |
|          ADR  =  ────────────────────────────────────────────────────────                         |
|                     IRC §414(s) Testing Compensation (Capped by §401(a)(17))                      |
|                                                                                                   |
|   • Exclude age-50 catch-up contributions under IRC §414(v).                                      |
|   • Round ADR to nearest hundredth of a percent (0.01%).                                          |
|                                                                                                   |
|   STAGE 3: COMPUTE GROUP ACTUAL DEFERRAL PERCENTAGES (ADPs)                                       |
|   • Calculate the UNWEIGHTED ARITHMETIC MEAN of ADRs separately for HCEs and NHCEs:               |
|                                                                                                   |
|                   Sum of Individual ADRs in Group                                                 |
|          ADP  =  ─────────────────────────────────                                                |
|                      Total Eligible Employees in Group                                            |
|                                                                                                   |
|   • NEVER divide total group deferrals by total group compensation!                               |
|                                                                                                   |
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Determining the Eligible Participant Population: Treas. Reg. §1.401(k)-6

A critical area of testing on the ASPPA QKA examination involves properly identifying which employees must be included in the ADP test. Under Treasury Regulation §1.401(k)-6, an "Eligible Employee" is defined as any employee who is directly or indirectly eligible to make a cash or deferred election under the plan for all or any portion of the plan year.

The Direct or Indirect Eligibility Standard

The statutory mandate requires including any employee who has satisfied the plan's age and service conditions under IRC §410(a) and reached an entry date during the plan year. The regulations enforce an expansive view of eligibility:

1. Zero-Percent Deferrers ($0 Deferral): An employee who satisfies eligibility conditions but chooses not to execute a salary reduction agreement, or who elects a salary deferral rate of 0.00%, is an eligible employee. Their ADR is 0.00%, and this zero MUST be factored into the group average.
2. Mid-Year Terminations: An employee who meets eligibility requirements, enters the plan, and subsequently terminates employment mid-year (whether on February 1 or November 30) is an eligible employee for the plan year. Their elective deferrals made prior to termination are divided by their testing compensation earned during the testing period.
3. Mid-Year Entrants: An employee who reaches a semi-annual or monthly entry date mid-year (e.g., July 1 in a calendar year plan) is an eligible employee for that plan year.
4. Employees Suspended Due to Plan Provisions (e.g., Loan Defaults): If an employee's deferral privileges are suspended under the terms of the plan document—for instance, due to a default on a participant loan under IRC §72(p) or failure to maintain required minimum account documentation—the employee remains an eligible employee for ADP testing throughout the suspension period.

[!IMPORTANT] Elimination of Post-Hardship Contribution Suspensions: Under pre-2019 Treasury regulations, plans were required to suspend an employee from making elective deferrals for at least six months following the receipt of a hardship distribution under the safe harbor hardship rules. During that mandatory 6-month suspension, the employee was still treated as an eligible employee for the ADP test. However, under the Bipartisan Budget Act of 2018 (BBA) and updated Treas. Reg. §1.401(k)-1(d)(3)(iii), plans are strictly prohibited from imposing a post-hardship suspension on elective deferrals for hardship distributions made on or after January 1, 2020. Today, participants may continue deferring immediately following a hardship withdrawal.

Statutory Exclusions from the Eligible Population

The only individuals who are excluded from the ADP test are:

• Employees who have not yet satisfied the plan's statutory age and service conditions (e.g., age 21 and 1 year of service under IRC §410(a)(1));
• Employees who belong to an excludable statutory job category explicitly excluded under the written plan document and IRC §410(b)(3), such as union employees covered by a bona fide collective bargaining agreement or non-resident aliens with no U.S.-source income;
• Employees carved out under the Otherwise Excludable Disaggregation Rule of IRC §410(b)(4)(B) (where early entrants under age 21 or with less than 1 year of service are tested in a separate, disaggregated ADP test).

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Defining the Actual Deferral Ratio (ADR)

Under Treasury Regulation §1.401(k)-2(a)(2), the Actual Deferral Ratio (ADR) represents the fundamental building block of the ADP test. It is computed individually for every eligible employee to measure the proportion of compensation deferred into the trust:

$\text{ADR}_i = \frac{\text{Includible Elective Deferrals of Employee } i}{\text{IRC Section 414(s) Testing Compensation of Employee } i}$

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|                             ADR COMPUTATION RULES & STATUTORY CAPS                                |
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|                                                                                                   |
|   1. NUMERATOR: INCLUDIBLE ELECTIVE DEFERRALS                                                     |
|      • Pre-tax elective deferrals under IRC §402(g).                                              |
|      • Designated Roth contributions under IRC §402A.                                             |
|      • EXCLUDE: Age-50 catch-up contributions under IRC §414(v).                                  |
|      • EXCLUDE: Deferrals returned as excess deferrals under IRC §402(g) to NHCEs.                 |
|      • INCLUDE: Deferrals returned as excess deferrals under IRC §402(g) to HCEs!                  |
|                                                                                                   |
|   2. DENOMINATOR: IRC §414(s) TESTING COMPENSATION                                                |
|      • Must satisfy an objective nondiscriminatory definition under IRC §414(s).                  |
|      • Subject to the statutory annual compensation cap under IRC §401(a)(17):                     |
|          - 2024 Limit: $345,000                                                                   |
|          - 2025 Limit: $350,000                                                                   |
|      • Full-Year vs. Period of Participation election must apply uniformly.                       |
|                                                                                                   |
|   3. REGULATORY ROUNDING CONVENTION                                                               |
|      • Calculated to the nearest HUNDREDTH OF A PERCENT (0.01% / 0.0001).                         |
|      • Examples: 5.6667% rounds to 5.67%; 4.1250% rounds to 4.13%.                                |
|                                                                                                   |
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The IRC §401(a)(17) Annual Compensation Limit

When calculating an employee's ADR, compensation taken into account in the denominator cannot exceed the annual statutory compensation ceiling established under IRC §401(a)(17) ($345,000 for 2024; $350,000 for 2025). If an executive earns $500,000 in 2024 and defers $23,000, their ADR is not $23,000 / $500,000 (4.60%). The denominator is capped at $345,000, resulting in an ADR of:

$\text{ADR} = \frac{\$23,000}{\$345,000} = 6.67\%$

Full-Year vs. Period of Participation Compensation

Under Treas. Reg. §1.401(k)-2(a)(3)(iii), a plan document may specify whether testing compensation in the denominator includes compensation for the entire 12-month plan year, or only compensation earned during the portion of the plan year in which the employee was an eligible participant:

• Full-Year Compensation: Total §414(s) compensation earned from January 1 through December 31. This is the regulatory default.
• Period of Participation Compensation: Compensation earned strictly from the employee's plan entry date through December 31 (or termination date).

[!TIP] Planning Impact of Participation Compensation: Using participation compensation increases the ADR for mid-year entrants because their deferrals are divided by a smaller compensation denominator (e.g., 6 months of pay instead of 12). If mid-year entrants are predominantly NHCEs who defer at solid rates, electing participation compensation can substantially increase the NHCE group ADP, making it easier for HCEs to pass the test!

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Includible vs. Excluded Contributions in the ADP Test

Properly classifying contribution streams is paramount. On the ASPPA QKA exam, question stems often present a mixed census containing multiple types of payroll deductions and contributions:

The Age-50 Catch-Up Rule: IRC §414(v)

Under IRC §414(v), participants who attain age 50 by the end of the calendar year are permitted to make additional catch-up contributions above the standard IRC §402(g) deferral limit ($7,500 catch-up limit in 2024 and 2025; standard limit $23,000 in 2024 and $23,500 in 2025).

Under Treas. Reg. §1.414(v)-1(d), catch-up contributions are STRICTLY EXCLUDED from the initial ADP test. When an employee age 50 or older defers up to the combined maximum ($23,000 base + $7,500 catch-up = $30,500 in 2024), the administrator must strip out the $7,500 catch-up portion before calculating the ADR. Only the base $23,000 deferral is placed in the ADR numerator!

[!WARNING] The Post-Testing Catch-Up Recharacterization Trap: While catch-up contributions are never included in the initial ADP test, if the plan subsequently fails the ADP test, excess contributions allocated to an HCE who is age 50 or older can be recharacterized as catch-up contributions (up to their unused §414(v) limit), avoiding the need to issue a taxable corrective refund! Candidates must never confuse the initial testing exclusion with the post-test corrective recharacterization.

The Excess Deferral Rule: HCE vs. NHCE Asymmetry

If an employee exceeds the statutory annual deferral limit under IRC §402(g) across all plans ($23,000 in 2024):

• For an HCE: Under Treas. Reg. §1.402(g)-1(e)(1)(ii), excess deferrals must remain in the ADP test numerator, even if the excess is timely distributed to the HCE by April 15 of the following year! Congress enacted this rule to prevent HCEs from intentionally deferring beyond statutory limits to manipulate testing.
• For an NHCE: Excess deferrals distributed by April 15 are excluded from the ADP test numerator if the excess occurred under plans of the same employer or controlled group. If not distributed, they remain in the test.

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Mathematical Mechanics: Unweighted Average vs. Weighted Average

The most pervasive computational error in retirement plan administration is calculating the group ADP as a weighted average. Under Treasury Regulation §1.401(k)-2(a)(2)(i), the Actual Deferral Percentage for a group is strictly defined as the unweighted arithmetic mean of the individual ADRs of all eligible employees in that group:

$\text{Group ADP} = \frac{\sum_{i=1}^n \text{ADR}_i}{n} = \frac{\text{ADR}_1 + \text{ADR}_2 + \dots + \text{ADR}_n}{n}$

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|                   THE FATAL TESTING ERROR: "AVERAGE OF RATIOS" VS. "RATIO OF SUMS"                 |
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|                                                                                                   |
|   CORRECT REGULATORY METHOD (Average of Ratios):                                                  |
|   1. Calculate ADR for each participant individually: ADR_i = Deferral_i / Comp_i                |
|   2. Sum the individual ADRs: Total ADRs = ADR_1 + ADR_2 + ... + ADR_n                           |
|   3. Divide by the headcount of eligible employees: Group ADP = Total ADRs / n                    |
|                                                                                                   |
|   FATAL ILLEGAL METHOD (Ratio of Sums / Weighted Average):                                        |
|   1. Sum all deferrals across the group: Total Deferrals = Def_1 + Def_2 + ... + Def_n           |
|   2. Sum all compensation across the group: Total Comp = Comp_1 + Comp_2 + ... + Comp_n           |
|   3. Divide total dollars by total dollars: Weighted % = Total Deferrals / Total Comp            |
|                                                                                                   |
|   • THE RATIO OF SUMS IS COMPLETELY VOID UNDER IRC §401(k)(3) AND DISQUALIFIES THE TEST!          |
|                                                                                                   |
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The Impact of Zero-Percent Deferrers

Every eligible non-deferring employee enters the ADP calculation with an ADR of 0.00%. Because the group ADP is an unweighted average, every zero-deferrer adds 0.00% to the numerator while adding 1 full person to the denominator ($n$).

Consider an NHCE group of 5 employees: 4 employees defer 10.00%, and 1 employee defers 0.00%:

• Correct ADP (including zero): $\frac{10.00% + 10.00% + 10.00% + 10.00% + 0.00%}{5} = \frac{40.00%}{5} = \mathbf{8.00%}$
• Fatal Error (omitting zero): $\frac{40.00%}{4} = \mathbf{10.00%}$

Omitting non-deferring eligible employees artificially inflates the NHCE ADP (from 8.00% to 10.00%), creating a fraudulent passing result that can lead to IRS audit sanctions or plan disqualification.

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Step-by-Step Multi-Participant Census Worksheet

To illustrate the complete operational mechanics of Stage 1 and Stage 2, consider the following census for Apex Technologies for the 2024 calendar plan year. Apex sponsors an unstandardized 401(k) plan with immediate eligibility. The IRC §401(a)(17) compensation limit is $345,000, and the IRC §402(g) elective deferral limit is $23,000 ($7,500 catch-up limit under IRC §414(v)).

Apex Technologies 2024 Plan Census & Deferral Data

Detailed Calculation Notes:

1. Executive A (HCE): Age 54. Total deferrals of $30,500 include $7,500 of age-50 catch-up under IRC §414(v). The catch-up is excluded from initial testing ($30,500 - $7,500 = $23,000). Gross pay of $420,000 is capped at the §401(a)(17) limit of $345,000. $\text{ADR} = $23,000 / $345,000 = 6.6667% \rightarrow \mathbf{6.67%}$.
2. Executive B (HCE): Age 46. Contributed $11,000 pre-tax and $11,000 Roth ($22,000 total). Both are includible. $\text{ADR} = $22,000 / $220,000 = \mathbf{10.00%}$.
3. Executive C (HCE): Eligible HCE who chose not to defer. $\text{ADR} = \mathbf{0.00%}$.
4. Staff E (NHCE): Age 52. Deferred $4,800 pre-tax, $2,000 Roth, and $3,000 designated catch-up. Catch-up is excluded ($9,800 - $3,000 = $6,800). $\text{ADR} = $6,800 / $80,000 = \mathbf{8.50%}$.
5. Staff G & Staff J (NHCEs): Eligible employees who chose 0% deferral. Included in test with $\text{ADR} = \mathbf{0.00%}$.
6. Staff H (NHCE): Terminated employment August 1, 2024. Was an eligible employee during the plan year; pay earned while employed was $40,000. $\text{ADR} = $2,000 / $40,000 = \mathbf{5.00%}$.
7. Staff I (NHCE): Deferrals suspended October 1 due to plan loan default. Was eligible during the plan year; made $1,000 deferral on $50,000 compensation. $\text{ADR} = $1,000 / $50,000 = \mathbf{2.00%}$.

Group ADP Calculation:

HCE Group ADP (3 Eligible HCEs):

$\text{HCE ADP} = \frac{\text{ADR}_A + \text{ADR}_B + \text{ADR}_C}{3} = \frac{6.67\% + 10.00\% + 0.00\%}{3} = \frac{16.67\%}{3} = \mathbf{5.56\%}$

NHCE Group ADP (7 Eligible NHCEs):

$\text{NHCE ADP} = \frac{8.00\% + 8.50\% + 6.00\% + 0.00\% + 5.00\% + 2.00\% + 0.00\%}{7} = \frac{29.50\%}{7} = \mathbf{4.21\%}$

Side-by-Side Comparison: Unweighted Average vs. Illegal Weighted Average

[!CAUTION] Notice that using the illegal weighted average overstates the NHCE ADP as 5.07% (because higher-paid NHCE Staff D and E skew the dollars), whereas the true statutory unweighted average is only 4.21%! Relying on the weighted average would completely corrupt subsequent compliance testing.

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Common ASPPA QKA Exam Traps

• Exam Trap 1: The Weighted Average Trap ("Ratio of Sums"): Questions often present total dollars of deferrals and total payroll for each group. Unprepared candidates divide total deferrals by total payroll ($21,300 / $420,000 = 5.07%). The ADP test NEVER permits dividing total deferrals by total compensation; you must calculate individual ADRs first and take the unweighted arithmetic mean.
• Exam Trap 2: Omitting Zero-Deferral Eligible Participants: A question states that 10 NHCEs are eligible, but only 6 chose to contribute. Candidates calculate the NHCE ADP by dividing the sum of the 6 deferrers' ADRs by 6. The denominator must include all 10 eligible employees ($n = 10$). Omitting the 4 zeros is an automatic testing failure.
• Exam Trap 3: Including Catch-Up Contributions in the Initial ADP Test: A participant age 50+ defers $30,500. Candidates calculate the ADR using the entire $30,500. Under IRC §414(v), the $7,500 catch-up contribution is strictly excluded from the initial ADP test; only the base $23,000 is tested.
• Exam Trap 4: Forgetting the IRC §401(a)(17) Compensation Limit: An executive earns $450,000 and defers $23,000. Candidates calculate the ADR as $23,000 / $450,000 = 5.11%. Compensation is statutorily capped at $345,000 (for 2024), yielding an ADR of $23,000 / $345,000 = 6.67%.
• Exam Trap 5: Excluding Terminated Employees Who Were Eligible Mid-Year: An employee works from January through April, contributes $1,500 on $30,000 of compensation, and quits. Candidates omit the employee because they are not employed on the last day of the plan year. Eligibility for ADP is determined based on the entire plan year; mid-year terminations who were eligible MUST be included in the ADP test!