Glossary term
Actual Deferral Percentage (ADP) Test
The Actual Deferral Percentage test is a 401(k) nondiscrimination test that compares elective deferral rates for highly compensated and non-highly compensated employees.
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What Is the Actual Deferral Percentage Test?
The Actual Deferral Percentage test, or ADP test, is a 401(k) nondiscrimination test that compares elective deferral rates for highly compensated employees with those for non-highly compensated employees. It is one of the main annual tests for traditional 401(k) plans that are not designed to satisfy a safe harbor.
The test is meant to make sure the ability to defer salary into the plan is broadly used and not concentrated among owners and higher-paid employees.
Key Takeaways
- The ADP test reviews employee elective deferrals in many traditional 401(k) plans.
- It compares highly compensated employees with non-highly compensated employees.
- Catch-up contributions are generally not counted in the ADP test.
- Failed testing can cause refunds to HCEs, corrective contributions, or plan design changes.
How Deferral Testing Works
The ADP test groups eligible employees into highly compensated employees and non-highly compensated employees. It then compares average deferral percentages. If highly compensated employees defer too much relative to the rest of the workforce, the plan can fail.
The exact calculation depends on plan terms and IRS rules, but the financial message is simple: participation across the employee base matters. If rank-and-file employees do not contribute much, owners and executives may not be able to contribute as much as the statutory dollar limit would otherwise suggest.
Plan Feature | ADP Testing Role |
|---|---|
Employee elective deferrals | Main contribution type measured by the test. |
HCE group | Higher-paid or ownership group subject to comparison limits. |
NHCE group | Baseline group used to measure broader participation. |
Safe harbor design | May let the plan avoid annual ADP testing if requirements are met. |
What Employees May Notice
A failed ADP test can lead to excess contributions being returned to highly compensated employees. That can be frustrating because the employee may have tried to maximize contributions but later receives a taxable refund and loses some tax-deferred savings room.
Employers may respond by improving enrollment, adding automatic escalation, changing matching formulas, or adopting safe harbor contributions. Those design choices can make the plan more predictable for both business owners and employees.
The Bottom Line
The ADP test is a 401(k) fairness test for employee salary deferrals. It connects employee participation, plan design, and the ability of highly compensated employees to save at higher levels.