What Is the 401(k) Coverage Test?

Coverage asks who gets through the door.

ADP and ACP test what happens after employees are inside.

Section 410(b) generally requires a qualified retirement plan to benefit a broad enough group of nonhighly compensated employees, or NHCEs, rather than concentrating access among highly compensated employees, or HCEs.^[1]

For the 401(k) elective-deferral portion, there is a rule that often surprises people:

An employee who is eligible to make a 401(k) deferral generally counts as benefiting for coverage even if the employee elects to contribute 0%.^[8]

That is almost the opposite of how the same employee affects ADP testing.

In ADP:

0% deferral = 0% ratio

In 401(k) coverage:

eligible to defer = generally benefiting

The tests answer different questions.

Key Takeaways

- Section 410(b) is a minimum coverage rule.^[1] - It asks whether enough NHCEs benefit under the plan relative to HCEs. - Coverage is different from: - Section 410(a) eligibility - ADP testing - ACP testing - top-heavy testing - For a 401(k) cash-or-deferred arrangement, an employee eligible to defer generally counts as benefiting even with a 0% election.^[8] - IRS describes three principal Section 410(b) pathways: 1. at least 70% of NHCEs benefit 2. the NHCE benefiting percentage is at least 70% of the HCE benefiting percentage 3. the plan satisfies the nondiscriminatory classification and average benefit tests.^[1] - The ratio percentage formula is: NHCE benefiting percentage ÷ HCE benefiting percentage.^[1][5] - A plan can satisfy the ratio test even when fewer than 70% of NHCEs benefit if HCE coverage is also sufficiently low. - The HCE list must be correct. INV-084 covers HCE classification. - Some employees can be disregarded under statutory or regulatory rules, but labels such as part-time, hourly, warehouse or remote are not automatic Section 410(b) exclusions. - Employees of related businesses can have to be included under controlled-group or affiliated-service-group rules.^[3][7] - The 401(k), 401(m) and profit-sharing portions of a single plan document can require separate coverage treatment.^[5][6][8] - Passing ADP and ACP does not prove the plan passes coverage.

Eligibility and Coverage Are Different Rules

This distinction is fundamental.

Section 410(a)

Addresses minimum participation rules, including age and service limits and entry timing.^[1][2]

Section 410(b)

Asks whether the group that benefits is sufficiently broad and nondiscriminatory.^[1]

A plan can satisfy one and fail the other.

Example: The Document Excludes a Division

Employer has:

• 20 headquarters employees
• 30 warehouse employees

Plan document says:

Only headquarters employees are eligible

The employer follows that language perfectly.

There is no operational failure caused by accidentally ignoring the document.

But if the excluded warehouse group is heavily NHCE and headquarters contains most HCEs, the plan can still fail Section 410(b).

Following a discriminatory plan design correctly does not make the design nondiscriminatory.

The Employer Population Comes Before the Participant List

A common testing mistake begins with:

"Send us a list of everyone in the plan."

That is too late in the process.

Coverage testing first asks who belongs in the employer population.

That can require information about:

• all employees
• ownership
• related companies
• controlled groups
• affiliated service groups
• acquisitions
• dispositions
• certain leased employees
• collective bargaining status
• nonresident alien status
• age and service

The participant list is an output of plan rules.

It is not automatically the correct coverage denominator.

The Basic 70% NHCE Test

IRS states that a plan can satisfy Section 410(b) if it benefits at least:

70% of NHCEs.^[1]

Simplified:

NHCEs benefiting ÷ nonexcludable NHCEs

must be at least:

70%

Example: 70 of 100 NHCEs

Nonexcludable NHCEs:

100

NHCEs benefiting:

70

Percentage:

70 ÷ 100 = 70%

The plan satisfies the basic percentage test.

This test does not require a separate HCE percentage calculation.

69% Is Not 70%

Nonexcludable NHCEs:

100

NHCEs benefiting:

69

Result:

69%

The basic percentage test fails.

The analysis does not necessarily end there.

The plan may still satisfy:

• the ratio percentage test
• the average benefit test

depending on the facts.

The Ratio Percentage Test

The ratio percentage test compares rates, not headcounts.

First calculate:

NHCE benefiting percentage

NHCEs benefiting ÷ total nonexcludable NHCEs

Then calculate:

HCE benefiting percentage

HCEs benefiting ÷ total nonexcludable HCEs

Then:

NHCE benefiting percentage ÷ HCE benefiting percentage

The result generally must be at least:

70%.^[1][5]

Example: Less Than 70% of NHCEs Can Still Pass

Employer has:

HCEs

10 total 6 benefiting

HCE benefiting percentage:

60%

NHCEs

90 total 40 benefiting

NHCE benefiting percentage:

44.44%

The basic 70% NHCE percentage test fails.

Now run the ratio test:

44.44% ÷ 60% = 74.07%

The ratio exceeds 70%.

The plan can satisfy the ratio percentage test despite covering fewer than half of its NHCEs.

That result looks strange only if the rule is mistaken for a universal 70%-of-NHCE headcount requirement.

Why the Ratio Test Works That Way

Section 410(b) is concerned with disproportionate coverage favoring HCEs.

In the prior example:

• 60% of HCEs benefit
• 44.44% of NHCEs benefit

NHCE coverage is lower, but it is still more than 70% of the HCE coverage rate.

The test measures relative access.

Example: 65% NHCE Coverage Can Fail

HCEs benefiting:

100%

NHCEs benefiting:

65%

Ratio:

65% ÷ 100% = 65%

The plan fails the ratio percentage test.

The plan also fails the basic 70% NHCE test.

That is the classic fact pattern where the employer needs to:

• expand coverage
• evaluate the average benefit test
• or analyze another permitted correction/design approach

The Ratio Does Not Divide NHCE Participants by HCE Participants

Assume:

• 200 NHCEs, 120 benefiting
• 10 HCEs, 10 benefiting

A mistaken calculation is:

120 ÷ 10 = 1,200%

That number is meaningless for Section 410(b).

The correct calculation is:

NHCE benefiting percentage:

120 ÷ 200 = 60%

HCE benefiting percentage:

10 ÷ 10 = 100%

Ratio percentage:

60% ÷ 100% = 60%

Result:

Fail

Coverage testing compares group percentages, not raw group sizes.

Who Counts as "Benefiting"?

The answer depends on the plan component.

For a normal defined contribution contribution source, an employee generally needs an allocation or other benefit recognized under the applicable rules.^[5][8]

The 401(k) elective-deferral portion has a special rule.

A 0% Deferrer Can Still Benefit for 401(k) Coverage

IRS guidance states that an employee eligible to make an elective contribution under a qualified cash-or-deferred arrangement is treated as benefiting for Section 410(b) coverage purposes even if the employee makes no deferral.^[8]

Suppose an employee is:

• eligible for the 401(k)
• has access to payroll deferrals
• elects 0%

For coverage of the 401(k) elective-deferral arrangement:

generally benefiting

For ADP testing:

0% Actual Deferral Ratio

One person can therefore help the coverage test and hurt the ADP average.

That is not inconsistent.

The tests measure different things.

Example: Eligible But Does Not Save

Employer has 100 NHCEs.

All 100 are eligible to defer.

Only 25 actually contribute.

For the 401(k) deferral component's coverage test, the special benefiting rule can treat all 100 eligible employees as benefiting.^[8]

For ADP, the 75 eligible noncontributors generally enter with 0% ratios.

Coverage can look excellent while ADP is weak.

Coverage vs ADP vs ACP vs Top-Heavy

A plan can pass three and fail the fourth.

There is no universal annual "nondiscrimination pass."

The Average Benefit Test

If the straightforward percentage or ratio paths fail, Section 410(b) can still be satisfied through the average benefit test.^[1][5]

This is not merely another headcount formula.

It generally requires both:

1. a nondiscriminatory classification test
2. an average benefit percentage test.^[1][5]

The second component generally requires the NHCE average benefit percentage to be at least:

70%

of the HCE average benefit percentage.^[1]

The Classification Must Be Defensible

The average benefit test does not let an employer invent any group and call it reasonable.

The classification component evaluates whether the group benefiting under the plan is nondiscriminatory under the regulatory framework.

That analysis can involve:

• objective business classifications
• the plan's ratio percentage
• regulatory safe-harbor and unsafe-harbor percentages
• facts and circumstances

This is specialist testing.

A sponsor should not use the average benefit test as a casual fallback spreadsheet when the ratio percentage is 68%.

Example: Why the Average Benefit Test Is Different

Two plans each cover:

55% of NHCEs

and:

100% of HCEs

Both fail the 70% ratio percentage test.

Plan A may provide substantial employer benefits broadly across NHCEs through other qualified arrangements.

Plan B may concentrate nearly all employer-provided benefits among HCEs.

The average benefit analysis can distinguish those fact patterns because it looks beyond a single headcount ratio.

That complexity is the point.

Which Employees Can Be Excluded?

Section 410(b) does not require every person on payroll to remain in every test denominator.

IRS identifies permitted exclusions including certain:^[1]

• employees covered by a collective bargaining agreement
• nonresident aliens with no U.S.-source earned income

Age and service rules can also allow employees who have not satisfied applicable minimum conditions to be disregarded.^[2]

The exact exclusions depend on the regulation and facts.

Part-Time Is Not an Automatic Section 410(b) Exclusion

An employer cannot safely tell the TPA:

"Remove all part-timers."

The question is whether those employees are excludable under:

• statutory age/service rules
• the plan's valid eligibility provisions
• special long-term part-time rules where applicable
• another specific coverage rule

Job schedule alone is not a universal exclusion.

A 25-hour-per-week employee can be fully relevant to coverage testing.

Job Title Is Not an Automatic Exclusion

The same problem arises with labels such as:

• hourly
• seasonal
• commission-only
• warehouse
• remote
• clerical
• field staff
• Division B

A plan document can use employee classifications in certain circumstances.

Section 410(b) still tests whether the resulting coverage is nondiscriminatory.

Writing the exclusion into the document is not the end of the analysis.

Union Employees

IRS states that employees included in a unit covered by a collective bargaining agreement can be excluded from consideration for Section 410(b) when the applicable requirements are met.^[1]

That rule exists because retirement benefits for that group can be the subject of collective bargaining.

Do not generalize it to:

"Anyone who belongs to a union is excluded."

The actual bargaining-unit and retirement-benefit facts matter.

Nonresident Aliens

IRS also identifies nonresident aliens receiving no U.S.-source earned income from the employer as a group that can be excluded for Section 410(b) purposes.^[1]

This can matter for multinational employers.

Citizenship alone is not the test.

The rule concerns tax and compensation status under the applicable statutory framework.

Otherwise Excludable Employees

Some plans are more generous than federal minimum eligibility rules.

Example:

Plan allows employees to enter at:

age 18 with immediate eligibility

Federal qualified-plan rules would generally permit a plan to wait until later age/service conditions, subject to the applicable rules.^[1][2]

Employees admitted earlier can be otherwise excludable employees.

IRS guidance permits specified separate-testing approaches when the plan language and regulatory conditions are satisfied.^[2]

Why Separate Testing Can Matter

Assume a company hires many young entry-level employees.

The plan admits them immediately.

These employees:

• are mostly NHCEs
• often defer 0%
• would not yet have completed the maximum age/service conditions allowed under Section 410(a)

Testing everyone together can produce a poor ADP result.

Under permitted otherwise-excludable-employee rules, the employer may be able to separate the population into:

• employees who have satisfied the applicable statutory age/service threshold
• employees who have not

Each component still needs to satisfy the relevant coverage requirements.^[2]

This is not an informal data filter.

IRS says plan language is required for the testing method.^[2]

Coverage and ADP Can Use the Same Population Architecture

The otherwise-excludable-employee rules show how coverage architecture can feed ADP testing.

If the plan validly separates populations for Section 410(b), it can in specified circumstances perform separate ADP tests for those populations.^[2]

That can materially change an employer's result.

The plan document needs to support the method before the employer relies on it.

Related Employers Can Expand the Denominator

A sponsor should not assume:

different EIN = different coverage universe

Employees of entities under common control or within an affiliated service group can have to be considered under the retirement-plan employer rules.^[3][7]

IRS's internal-control guidance specifically tells sponsors to determine whether related employers create:

• a controlled group
• an affiliated service group.^[3]

That question belongs upstream of annual testing.

Example: Owner Has Two Companies

Owner controls:

Company A

10 employees 401(k) plan covers all 10

Company B

40 employees no retirement plan

If the companies form a controlled group under the applicable ownership rules, the testing population may not stop at Company A's payroll.

The 40 employees in Company B can change the Section 410(b) result.

A 100% participation rate inside Company A does not automatically mean the plan has 100% coverage for the statutory employer group.

Affiliated Service Groups Can Be Less Obvious

Common ownership is not the only relationship that can matter.

Certain service organizations can be treated together under affiliated-service-group rules based on ownership and service relationships.

This can arise in structures involving:

• medical practices
• law firms
• consulting groups
• management/service companies
• professional entities

The exact Section 414 analysis is technical.

The practical control is simple:

tell the TPA about every related business and service entity before testing.

Certain Leased Employees Can Matter

Coverage testing can also require analysis of workers who are not on the sponsor's ordinary payroll when leased-employee rules apply.^[7]

This does not mean every staffing-agency worker belongs in the plan.

It means:

payroll source is not the legal definition of employee population.

The employer should flag material staffing arrangements for qualified-plan review.

One Plan Document Can Contain Several Coverage Tests

A combined 401(k) document can contain:

• elective deferrals
• matching contributions
• employee after-tax contributions
• profit-sharing contributions

Those sources are not always one Section 410(b) plan for testing purposes.

IRS guidance treats the Section 401(k) and Section 401(m) portions as separate components for coverage, and profit-sharing contributions can require separate coverage analysis as well.^[5][6][8]

Example: Deferral Coverage Passes, Profit Sharing Fails

Employer lets every eligible employee make 401(k) deferrals.

Deferral component:

broad coverage

The employer's profit-sharing formula allocates contributions only to:

management division

If that division is HCE-heavy, the profit-sharing component can fail coverage even though every employee has access to the 401(k).

The statement:

"Everyone can participate in our 401(k)"

does not answer whether every employer contribution component passes Section 410(b).

The Match Can Have Its Own Coverage Population

Suppose all employees can defer.

Only salaried employees are eligible for matching contributions.

The 401(k) elective-deferral component can satisfy coverage because everyone can make a deferral.

The 401(m) matching component still has to satisfy its applicable coverage requirements.^[5][6]

INV-088 explains ACP testing after the matching population is established.

Coverage comes first:

Who is eligible for the match?

ACP comes next:

Are the matching rates nondiscriminatory?

Safe Harbor Does Not Eliminate Coverage

Safe-harbor design can provide relief from ordinary ADP and, for qualifying matching structures, ACP testing.

That does not turn Section 410(b) off.

A qualified cash-or-deferred arrangement still has a minimum coverage requirement.^[4][5]

A safe-harbor plan that excludes an impermissibly narrow NHCE group can still have a coverage problem.

INV-053 covers safe-harbor contribution structures.

Acquisitions Change the Population

IRS specifically tells plan sponsors to review Section 410(b) after:^[1]

• merger
• acquisition
• divestiture

The reason is straightforward.

The employee denominator can change overnight.

A plan that covered 80% of NHCEs before an acquisition can cover 30% after 200 new employees join the controlled group.

There Can Be Transition Relief

Section 410(b)(6)(C) provides transition relief for specified acquisitions and dispositions when conditions are met.^[4]

IRS Revenue Ruling 2004-11 explains that a plan can be treated as satisfying coverage during the statutory transition period when, among other requirements:

• the plan satisfied Section 410(b) immediately before the transaction
• plan coverage is not significantly changed during the transition period other than because of the transaction.^[4]

The transition period generally runs from the transaction date through the last day of the first plan year beginning after the transaction.^[4]

Example: Calendar-Year Acquisition

Company closes an acquisition:

June 30, 2026

Existing plan satisfied Section 410(b) immediately before closing.

Assuming the conditions for transition relief are met and no disqualifying significant change occurs, the maximum statutory transition period can extend through:

December 31, 2027

because that is the last day of the first plan year beginning after the transaction.^[4]

That does not mean the sponsor should wait until December 2027 to plan integration.

It means federal law can provide time to redesign coverage intelligently.

Significant Changes Can End Relief Early

IRS states that a significant change in the plan or its coverage during the transition period can curtail the Section 410(b)(6)(C) relief as of the change.^[4]

That matters when management wants to:

• amend eligibility
• change benefit formulas
• merge plans
• expand or contract covered groups

The acquisition relief is not a blanket freeze on compliance.

The proposed amendment has to be tested against the transition rule.

Business Transactions Should Reach the TPA Before They Close

Do not wait for the year-end census to disclose:

• acquisition
• disposition
• new subsidiary
• ownership shift
• management company
• related professional entity

Coverage testing is downstream of corporate structure.

INV-083 makes the same point for TPA data more broadly.

HCE Classification Still Has to Be Right

Coverage uses HCE and NHCE percentages.

So the result depends on INV-084's classification rules.

A missing:

• more-than-5% owner
• attributed family owner
• compensation-based HCE
• top-paid group election

can change both the HCE and NHCE percentages.

One misclassification can move the numerator and denominator of the ratio test.

Example: Misclassified Owner's Spouse

Initial population:

HCEs

5 total 5 benefiting 100%

NHCEs

10 total 7 benefiting 70%

Ratio:

70%

Pass.

Later, one of the 7 benefiting NHCEs is found to be the spouse of a more-than-5% owner and should have been classified as HCE under the applicable attribution rule.

Corrected:

HCEs

6 total 6 benefiting 100%

NHCEs

9 total 6 benefiting 66.67%

Ratio:

66.67%

Fail.

The employee never changed plans.

The classification changed the test.

Coverage Can Change Without a Plan Amendment

Suppose the document is unchanged for five years.

The employee population changes:

• more owners become HCEs
• a division hires many NHCEs
• an acquired business joins
• covered employees are promoted
• excluded group grows

IRS warns that demographic changes can affect how the plan satisfies Section 410(b).^[1]

Annual testing matters even when the document is untouched.

A Growing Business Can Outgrow Its Coverage Design

A 20-person firm starts with:

• owner
• four managers
• fifteen staff

Plan excludes one small employee group and passes coverage.

Five years later that excluded group has:

80 employees

while the covered group has barely grown.

The same document provision can now fail.

The rule did not change.

The business did.

Correction Starts With the Component That Failed

Do not correct "the plan" generically.

Identify whether the failure belongs to:

• 401(k) elective-deferral component
• 401(m) matching/after-tax component
• profit-sharing component
• another disaggregated portion

The correction depends on what employees should be treated as benefiting and what benefit or contribution must be provided.

Retroactive Expansion Can Be Available

IRS audit guidance describes a regulatory correction mechanism under Treasury Regulation 1.401(a)(4)-11(g)(3) that can permit a Section 401(k) or 401(m) plan to be retroactively amended to extend eligibility for coverage purposes within:

10½ months after the end of the plan year.^[8]

For a 401(k) coverage correction, the added NHCEs can require a QNEC based on the applicable regulatory correction method.^[8]

This is not the same correction as an ADP refund.

The current rule and plan facts should be verified before using it.

After the Specialized Correction Window

A demographic coverage failure can become a qualified-plan correction issue requiring analysis under the current IRS correction framework.

Possible paths can involve:

• retroactive amendment where permitted
• corrective employer contributions
• VCP
• other EPCRS treatment depending on the failure and timing

The proper correction should be based on current IRS procedures, not a generic contribution estimate.

The goal is not to make the spreadsheet pass.

It is to place affected employees in the economic position required by the applicable correction rule.

The Annual Coverage File

A useful annual file should preserve:

• complete employee census
• HCE/NHCE classification
• ownership information
• family attribution information
• controlled-group analysis
• affiliated-service-group analysis where relevant
• collective bargaining classification
• nonresident alien classification
• age/service status
• benefiting status by plan component
• coverage test calculation
• plan aggregation/disaggregation method
• acquisition/disposition analysis
• correction documentation if needed

A one-page PASS report is not enough to reconstruct the test later.

What to Review Before Accepting "410(b) PASS"

That review catches more errors than staring at the final ratio.

Frequently Asked Questions

What is the 401(k) coverage test?

It is the Section 410(b) minimum coverage analysis used to determine whether a qualified plan benefits a sufficiently broad group of NHCEs rather than disproportionately favoring HCEs.^[1]

Is coverage testing the same as ADP testing?

No. Coverage asks who benefits. ADP compares elective-deferral rates among eligible HCEs and NHCEs.

Does an employee who contributes 0% count for coverage?

For the 401(k) elective-deferral arrangement, an employee eligible to make an elective contribution generally counts as benefiting even if the employee elects 0%.^[8]

What is the 70% coverage test?

One statutory route is satisfied if at least 70% of applicable NHCEs benefit under the plan.^[1]

What is the ratio percentage test?

Divide the percentage of NHCEs benefiting by the percentage of HCEs benefiting. The result generally must be at least 70%.^[1][5]

Can fewer than 70% of NHCEs benefit and the plan still pass?

Yes. If HCE coverage is also below 100%, the ratio percentage can still reach 70%. The average benefit test can provide another route in appropriate cases.^[1]

What is the average benefit test?

It is a more complex alternative that generally requires both a nondiscriminatory employee classification and an NHCE average benefit percentage of at least 70% of the HCE average benefit percentage.^[1][5]

Are part-time employees automatically excluded?

No. Part-time status itself is not a blanket Section 410(b) exclusion. The employee must fit an applicable eligibility or exclusion rule.

Can union employees be excluded?

Certain employees in collectively bargained units can be excluded from Section 410(b) testing when the statutory conditions are met.^[1]

Can nonresident aliens be excluded?

Certain nonresident aliens with no U.S.-source earned income from the employer can be excluded.^[1]

Do employees at a commonly owned second company matter?

They can. Controlled-group and affiliated-service-group rules can require employees of related entities to be considered as employees of one employer for retirement-plan purposes.^[3][7]

Does a safe-harbor 401(k) avoid coverage testing?

No. Safe harbor can provide ADP and certain ACP relief, but the plan still must satisfy applicable minimum coverage requirements.^[4][5]

Is the match tested separately from elective deferrals?

The Section 401(k) elective-deferral portion and Section 401(m) matching/after-tax portion can require separate Section 410(b) treatment.^[5][6][8]

Can profit-sharing coverage fail while 401(k) coverage passes?

Yes. The employer nonelective contribution component can cover a different group and require its own coverage and nondiscrimination analysis.

What happens after an acquisition?

The expanded employer population can change coverage. Section 410(b)(6)(C) can provide transition relief for qualifying acquisitions or dispositions when its conditions are met.^[4]

How long can acquisition transition relief last?

The statutory transition period can run through the last day of the first plan year beginning after the transaction, assuming the applicable conditions continue to be satisfied.^[4]

Can a failed coverage test be corrected retroactively?

Certain coverage failures can be corrected through regulatory retroactive amendment and contribution mechanisms when the requirements and deadlines are met. Other failures can require EPCRS analysis.^[8]

The Population Reconciliation

Before running a Section 410(b) formula, reconcile four lists:

1. everyone employed by the statutory employer group
2. employees legally excludable from the test
3. remaining HCEs and NHCEs
4. employees benefiting under each separately tested plan component

Only then calculate the percentage.

If the TPA starts with the participant file rather than the employer population, the test can be wrong before the first formula is entered.

Sources & References

1. IRS: A Guide to Common Qualified Plan Requirements
2. IRS: Treatment of Otherwise Excludable Employees for Coverage and ADP Testing
3. IRS: Policies, Procedures and Internal Controls Self-Audit
4. IRS: Revenue Ruling 2004-11 — Section 410(b)(6)(C) Transition Rule
5. IRS: Internal Revenue Bulletin 2004-7 — Section 410(b) Coverage and Disaggregation
6. IRS: Internal Revenue Bulletin 2003-35 — 401(k)/401(m) Aggregation and Disaggregation
7. IRS: Controlled and Affiliated Service Groups — Employee Plans Training
8. IRS: 401(k) Audit Techniques — Coverage Tests

Educational Disclaimer

ROIStreet publishes educational content about retirement-plan coverage and nondiscrimination testing. This article is not legal, tax, fiduciary or plan-administration advice. Section 410(b) results depend on employer structure, employee classifications, plan components, exclusions, plan terms, business transactions and current law.

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