Nondiscrimination Testing


By The Human Interest Team

Many small companies offer retirement benefit plans for their employees, but the IRS has several rules regarding how those benefits impact income taxes. One of the tools used to measure compliance is nondiscrimination testing. 

Nondiscrimination testing: The basics

The IRS requires employers to run Nondiscrimination Testing (NDT) on certain retirement benefit plans in order to be compliant with ERISA and tax requirements. These tests assess the fairness of the retirement plans by ensuring that the benefits aren’t tailored to Highly Compensated Employees (HCEs) or key employees. The tests ensure that both the deferred wage and employer contribution mechanisms don’t unfairly benefit these individuals. 

Who qualifies as a “Highly Compensated Employee”?

The IRS releases guidelines defining who is and who is not a highly compensated employee:

Compensation (in 2021, 2022):

Highly Compensated Employee


Non-Highly Compensated Employee


Nondiscrimination testing requires each 401(k) sponsor to pass two tests each year: the Actual Deferral Percentage (ADP) test and the Actual Contribution Percentage (ACP) test. Sponsors can also choose between undergoing a Top-Heavy test or increasing employer contributions.

Two key factors determine if a 401(k) plan sponsor passes or fails:

  • Employee participation: Highly compensated employees are far more likely to participate than employees who worry they can’t afford to make contributions. This imbalance of type of participating employees can make sponsors fail nondiscrimination tests.

  • Employer contributions: Employers can make two types of contributions: matching contributions that match what employees have contributed to their accounts according to a pre-established formula, and nonelective contributions that are made regardless of an employee’s contributions. Having employer contributions can impact a plan’s likelihood of passing.

Cafeteria plan NDT

Cafeteria Plan NDTs have three test components:

  • Eligibility Test: This assesses whether the plan allows enough Non-Highly Compensated Employees (NHCEs) to become eligible and participate in the plan.

  • Benefits Test: This portion assesses whether or not the plan gives the same benefits to both NHCEs and HCEs.

  • Utilization Test: This portion measures which employees are actively participating in the plan, not just if employees can participate in the plan. Self-insured benefits have separate nondiscrimination testing requirements. Small businesses are the most likely to fail this portion of the plan.

When should NDT be performed?

Nondiscrimination testing should happen on an annual basis at the end of the plan year. Companies can also perform mid-year tests to correct any potential problems before the official tests. This is recommended because it’s much easier to fix in-progress problems than it is to adjust and retest after failing.

Actual Deferral & Actual Contribution Percentage Tests (ADP/ACP)

Both ADP and ACP tests assess the fairness of an employer’s 401(k) plan. ADP tests compare the salary deferrals between two employee groups: high compensated and non-highly compensated. It considers the deferral percentage or the percentage of an employee’s total salary that they contribute to the plan.

ACPs test the employer contributions percentages, not employee contributions. This test measures the employer contribution to employees as a percentage of the employee’s contribution to ensure highly compensated employees aren’t receiving unfairly high contributions.

If a plan sponsor fails either test, they have 12 months to correct the discrimination. Otherwise, they may incur pecuniary penalty fees from the IRS. They may also be subject to fiduciary liability and plan disqualification.

How ADP and ACP Tests work

ADP tests compare the average percentage of money a highly compensated employee will contribute to an employer-sponsored plan to the average percentage of money non-highly compensated employees. The ADP takes into consideration both pre-tax and Roth contributions, but not catch-up contributions for older employees. ACP tests follow the same general rules.

For the purposes of these tests, highly compensated employees are generally considered to be someone who has (or had in the last year) at least 5% company ownership, was paid at least $135,000, or was in the top 20% of paid employees. According to family attribution rules, being the spouse or child of someone with 5% ownership also makes that person a highly compensated employee. All other employees are considered non-highly compensated employees.

Applying the ADP/ACP Tests

As a general rule, the ADP and ACP tests require that highly compensated employees’ ADP doesn’t exceed non-highly compensated employees’ ADP by more than 2%. However, that threshold gets slightly more granular:

  • If the NHCE percentage is 0-2%, the HCE percentage can’t be more than double

  • If the NHCE percentage is 2-8%, the HCE percentage can’t be larger by more than 2%

  • For NHCE percentages over 8%, the HCE percentage can’t be more than 125% that percentage

Correcting an ADP/ACP Test

If you fail ACP/ADP IRS compliance testing, you can resolve the problem. Employers often fix the problem by returning excess funds to highly-compensated employees (which are then taxed as regular income). Some employers also set caps or strict rules to decrease the likelihood of failing in the first place. These caps can be determined through mid-year testing, so highly-compensated employees can contribute as much as possible without causing a nondiscrimination testing failure.

Also, a Safe Harbor 401(k) plan can give companies access to a 401(k) plan without the NDT requirement.

What is a Safe Harbor plan?

A Safe Harbor 401(k) provides both elective and nonelective employer contributions. Due to those contributions, the plan is exempt from NDT requirements, and many financial experts recommend choosing Safe Harbor plans because of that exemption. The requirements for a 401(k) to qualify as a safe harbor plan are:

  1. Elective (enhanced match): Company matches 100% of all employee 401(k) contributions, up to 4% of their compensation, OR

  2. Elective (basic match): Company matches 100% of all employee 401(k) contributions up to 3% of their compensation, plus a 50% match of the next 2% of their compensation, OR

  3. Non-elective: Company contributes 3% of each employee’s compensation, regardless of whether the employee also makes contributions.

Top-Heavy Test

A top-heavy test is the third type of nondiscrimination test that sponsors may need to undergo. Sponsors fail the test if over 60% of a plan’s assets are held by “key employees.” Key employees, who are different from highly-compensated employees, are defined as employees that fit any of these three descriptions as of 2022:

  1. Makes over $200,000 for 2022 and $185,000 for 2020-2021 (adjusted annually for inflation);

  2. Owns (or is a qualifying family member under the attribution rules) 5% of the company

  3. Owns (or is a qualifying family member under the attribution rules) 1% of the company and makes over $150,000

Important things to know about Non-discrimination testing

NDT is required by the IRS for all plans that fall under Section 125 of the tax code. This testing ensures the plan is equally accessible to all employers and doesn’t unfairly favor highly-compensated employees. Testing should happen each year at the end of the plan year, but companies should also undergo mid-year testing to reduce the risk of failure.

If you want to learn more about how to manage NDT requirements, reach out to our team today.

The Human Interest Team

Article By

The Human Interest Team

We believe that everyone deserves access to a secure financial future, which is why we make it easy to provide a 401(k) to your employees. Human Interest offers a low-cost 401(k) with automated administration, built-in investment advising, and integration with leading payroll providers.

Subscribe to our Retirement Roadmap newsletter

Retirement isn’t just a destination. It’s a journey, and we’re here to help you. Our newsletter delivers succinct and timely tips, reviewed by Financial Advisors, to help you navigate the path to financial independence.

By providing your email above or subscribing to our newsletter, you agree to our Privacy Policy. You also elect to receive communications from Human Interest.