Managing a 401(k) plan involves more than setting up payroll deductions and offering investment options. Employers also need to ensure their retirement plan remains compliant with IRS regulations designed to keep plans fair for all employees.

One of the most important compliance requirements is nondiscrimination testing.

For many HR teams, especially at growing companies, nondiscrimination testing can feel overly technical and difficult to navigate. Failed tests can lead to corrective distributions, unexpected employer contributions, administrative headaches, and frustration for both employees and leadership teams.

At Basic Capital, we believe retirement plan compliance should feel more transparent and manageable. Understanding how nondiscrimination testing works is an important part of building a healthier and more scalable retirement plan.

What Is 401(k) Nondiscrimination Testing?

401(k) nondiscrimination testing is a set of annual IRS tests designed to ensure retirement plans do not disproportionately benefit highly compensated employees (HCEs) over non-highly compensated employees (NHCEs).

In simple terms, the IRS wants to confirm that retirement plans are being used fairly across the organization and not functioning primarily as tax-advantaged savings vehicles for executives or business owners.

These tests compare contribution behavior between employee groups to evaluate whether participation and contribution levels remain balanced.

For many employers, nondiscrimination testing becomes more challenging as:

• Companies grow

• Compensation structures become more uneven

• Executive participation increases

• Employee participation rates fluctuate

The Main Types of Nondiscrimination Testing

There are several compliance tests that may apply to a traditional 401(k) plan, but the most common are the ADP and ACP tests.

ADP Testing

The Actual Deferral Percentage (ADP) test compares salary deferral rates between highly compensated employees and non-highly compensated employees.

The goal is to ensure executives and owners are not contributing significantly more to the plan than the broader employee population.

If participation among employees is too low while executives maximize contributions, the plan may fail the ADP test.

ACP Testing

The Actual Contribution Percentage (ACP) test focuses on employer matching contributions and after-tax employee contributions.

Like the ADP test, it compares participation behavior between highly compensated and non-highly compensated employees.

Plans with aggressive matching structures or uneven participation rates can sometimes encounter ACP testing issues even if ADP testing passes successfully.

What Happens if a Plan Fails Testing?

When a plan fails nondiscrimination testing, employers typically need to correct the imbalance.

Common correction methods include:

• Refunding contributions to highly compensated employees

• Making additional contributions to non-highly compensated employees

• Adjusting future contribution structures

• Revisiting plan design and participation strategies

For executives or business owners, failed testing can be frustrating because retirement contributions may need to be returned unexpectedly after year-end planning has already occurred.

For HR teams, failed testing can create additional administrative complexity and participant communication challenges.

Why Participation Rates Matter

One of the biggest factors influencing nondiscrimination testing outcomes is employee participation.

When participation rates among non-highly compensated employees remain low, plans are more likely to experience testing issues.

That’s why many employers focus on strategies designed to improve:

• Employee enrollment

• Contribution consistency

• Financial education

• Retirement readiness

• Overall engagement with the plan

At Basic Capital, we believe modern retirement experiences can play a meaningful role in improving participation behavior over time.

Employees increasingly expect retirement plans that feel:

• Easy to use

• Transparent

• Personalized

• Connected to their broader financial goals

Improving the participant experience often supports stronger long-term engagement.

How Safe Harbor 401(k) Plans Change Testing Requirements

One reason many growing companies eventually explore safe harbor 401(k) plans is because they can eliminate certain nondiscrimination testing requirements altogether.

Safe harbor plans require employers to commit to qualifying contribution structures, but in exchange, they generally bypass ADP and ACP testing requirements.

For companies struggling with repeated testing failures, a safe harbor structure can:

• Reduce compliance complexity

• Create more predictable contribution outcomes

• Allow executives to maximize contributions more consistently

• Improve administrative efficiency

At Basic Capital, we often see employers reevaluate plan design after several years of testing corrections or inconsistent participation behavior.

Companies exploring this option may also benefit from reviewing our:

• Safe Harbor 401(k) Guide for Plan Sponsors

• For Employers resources on modern retirement plan management

Why Modern Retirement Infrastructure Helps

Nondiscrimination testing becomes more manageable when employers have better visibility into plan data and participant behavior throughout the year.

Many HR teams still rely on fragmented systems, manual payroll coordination, and delayed reporting processes that make it harder to proactively identify compliance risks.

Modern retirement platforms can help simplify:

• Contribution tracking

• Payroll integration

• Real-time reporting

• Participation monitoring

• Compliance oversight

At Basic Capital, we believe retirement infrastructure should help reduce operational friction while improving the experience for employers, advisors, and participants alike.

Better technology can help HR teams move from reactive compliance management toward more proactive retirement plan oversight.

What HR Teams Should Monitor Throughout the Year

While nondiscrimination testing happens annually, preparation should happen year-round.

HR teams should regularly monitor:

• Participation rates across employee groups

• Contribution trends

• Executive deferral behavior

• Matching contribution structures

• Employee engagement with the plan

Addressing participation gaps earlier in the year can help reduce the likelihood of testing failures later on.

In many cases, improving communication, simplifying enrollment, and creating a more modern retirement experience can positively impact overall plan health.

Final Thoughts

401(k) nondiscrimination testing is designed to ensure retirement plans remain fair and balanced across the workforce.

For growing companies, repeated testing failures often signal broader opportunities to improve employee participation, modernize plan design, or evaluate whether a safe harbor 401(k) structure may be a better long-term fit.

At Basic Capital, we believe retirement plans should combine:

• Compliance simplicity

• Transparent plan management

• Better participant experiences

• Modern retirement technology

• Long-term retirement readiness

As retirement planning continues to evolve, employers with stronger visibility into participation and plan data may be better positioned to manage compliance proactively while supporting stronger retirement outcomes for employees.

Ready to simplify retirement plan administration and explore modern retirement plan options, including safe harbor 401(k) structures? Get started with Basic Capital to learn how our platform helps employers improve retirement outcomes, streamline compliance management, and create better participant experiences.