What Happens If a 401(k) Plan Fails Its Nondiscrimination Test?
Every year, many employer retirement plans run a set of required math checks behind the scenes. When the numbers don’t come out right, the fix often shows up as an unexpected check in a higher earner’s mailbox.
The short answer
Nondiscrimination testing compares how much higher-paid employees contribute to a 401(k) plan against how much everyone else contributes, to confirm the plan doesn’t disproportionately benefit a smaller group of earners. If a plan fails, it generally has to take corrective action within a set window, most commonly refunding a portion of the higher earners’ contributions or having the employer make an additional contribution for other participants. Left uncorrected, the plan’s tax-favored status could be at risk.
Why the testing exists
Retirement plans get favorable tax treatment partly because they’re meant to broadly benefit a workforce, not just concentrate advantages among the highest earners. Without a check like this, a plan could theoretically be designed so that mostly executives contribute and benefit, while participation among everyone else stays low. The testing compares contribution rates across groups to catch that kind of imbalance before it becomes a structural feature of the plan.
Common fixes when a plan fails
- Refunding excess contributions to higher earners. The plan can distribute the excess amount, adjusted for any investment earnings, back to the affected higher-paid employees, which is generally treated as taxable income to them in the year received.
- Making additional employer contributions. Instead of, or alongside, refunds, an employer can sometimes contribute more on behalf of lower-paid participants to bring the overall numbers into compliance.
- Recharacterizing contributions. In some plan designs, a portion of what was contributed can be reclassified in a way that helps the plan pass, depending on the plan’s structure and the type of contributions involved.
Timing matters
Corrections generally need to happen within a specific window after the plan year ends to avoid additional penalties or excise taxes. A correction made quickly tends to be simpler and less costly than one made after the deadline has passed, which is part of why plan sponsors often run preliminary test estimates during the year rather than waiting until year-end.
How this connects to correction programs more broadly
A failed nondiscrimination test is one of several issues that can be resolved through a structured plan correction program rather than treated as an isolated crisis. The refund itself is often processed as a type of corrective distribution, which has its own rules around calculation, taxation, and timing separate from a routine withdrawal.
What it looks like for an affected employee
An employee who contributed close to the maximum allowed amount, and who happens to be classified as a higher earner for testing purposes, might unexpectedly receive a check representing a portion of their own contributions, along with any investment growth on that amount. It can feel like a penalty, but it’s really a mechanical consequence of the plan-wide math not working out, not a reflection of anything the individual employee did.
The takeaway
A failed nondiscrimination test doesn’t mean a 401(k) plan has done something wrong on purpose. It means the plan-wide numbers didn’t line up with the rules meant to keep contributions broadly balanced, and the plan has a defined set of tools — refunds, additional contributions, or recharacterization — to bring things back into line, usually within a fairly short window after the plan year closes.