Section 125 Nondiscrimination Testing: The Annual Compliance Chore Nobody Explains

Plain English Benefits · Updated September 12, 2026 · Education, not tax advice

Short Answer

Section 125 nondiscrimination testing is an annual compliance requirement that proves your cafeteria plan doesn't disproportionately benefit highly compensated employees or key employees. Every employer running a Section 125 cafeteria plan—even a simple premium-only plan—must test. If you fail, you either fix the plan mid-year or some employees lose their pre-tax benefit and owe back taxes. Most failures trace to low participation among rank-and-file employees or a plan design that caps benefits too tightly for non-executives.

Why This Test Exists

The IRS created Section 125 to let employees pay for benefits with pre-tax dollars. That's a tax break. Tax breaks attract scrutiny. Congress decided decades ago that pre-tax benefit programs can't become executive perks—they have to be available to the broader workforce on reasonable terms, and participation patterns have to reflect that.

Nondiscrimination testing is the enforcement mechanism. You run the numbers every year. If the test shows your plan favors the highly paid, you lose the tax advantage for those employees until you fix it.

This isn't theoretical. Employers fail these tests regularly, especially small businesses where a few owners and managers drive most of the enrollment.

Who Has to Test

Every employer sponsoring a Section 125 cafeteria plan. That includes:

• Premium-only plans (POPs). Even though a POP only covers insurance premiums, it's still a cafeteria plan under Section 125, and testing applies.
• Full cafeteria plans offering FSAs, HSA contributions, or dependent care accounts alongside premium conversion.
• Plans covering one employee. If you're a solo business owner with a Section 125 plan, you still test. You'll likely fail the key employee test automatically, but the IRS requires documentation.

The only exemption: if your plan truly covers zero highly compensated or key employees, testing becomes a formality. That almost never happens in practice.

The Three Tests You're Running

Nondiscrimination testing actually comprises three separate tests. You have to pass all three.

1. Eligibility Test

This test asks: are rank-and-file employees allowed into the plan on reasonable terms, or did you write the eligibility rules to keep them out?

The IRS looks at your plan document. If it says "must work 30+ hours per week" or "managers only," you probably fail. The safe harbor: the plan must benefit a group that meets one of the IRS classifications—typically, you need to cover at least 70% of all non-highly compensated employees.

Most employers pass the eligibility test by making the plan available to everyone who works a minimum number of hours. Where employers stumble: setting the hour threshold so high that part-timers are excluded, and part-timers make up most of the non-executive workforce.

2. Benefits Test

This test asks: do the actual benefits offered favor the highly paid?

The IRS examines the menu. If executives can contribute significantly more to an FSA, or if they get richer benefits, you fail. Safe harbor: offer the same dollar limits and the same benefit options to everyone. If your FSA cap is $3,200 for all employees and your health premium deduction works the same way for the receptionist and the VP, you pass.

The trap: tiered plans where contribution limits scale with salary. That design fails the benefits test unless you can prove the tiers are nondiscriminatory under the facts-and-circumstances analysis, which is harder than it sounds.

3. Concentration Test

This is the test that catches most small employers. It asks: are key employees hogging a disproportionate share of the plan's total value?

The rule: non-taxed benefits provided to key employees can't exceed 25% of the total non-taxed benefits provided to all employees under the plan.

Who counts as a key employee? Officers earning above a threshold (indexed annually, roughly $220,000 in recent years), more-than-5% owners, and more-than-1% owners earning over $150,000. If you're a ten-person company and three of those people are owners, those three are likely key employees.

Run the math: total up everyone's pre-tax benefit elections for the year. If the key employees' total is more than 25% of the company-wide total, you fail.

Why this test matters most for small businesses: in a 15-person company, if two owner-operators each put $3,000 into an FSA and deduct $12,000 in health premiums, but rank-and-file employees mostly waive the FSA and half of them are on a spouse's insurance, the key employees' share of the plan can easily hit 40% or 50%. Failure.

Who Counts as Highly Compensated

Separate from key employees, the IRS defines highly compensated employees (HCEs) for the eligibility and benefits tests. For most plan years, that means anyone who:

• Owned more than 5% of the business at any time during the current or prior year, or
• Earned more than the indexed threshold (around $155,000 in recent years) in the prior year.

You test against this group for eligibility and benefits. You test against key employees for concentration. The groups overlap but aren't identical—a high earner who isn't an owner might be highly compensated but not a key employee.

What Happens If You Fail

The IRS doesn't fine you directly for failing nondiscrimination testing. Instead, the highly compensated or key employees lose their tax benefit. The plan has to treat their contributions as taxable income and report it on their W-2. They owe income tax and payroll tax on money they thought was pre-tax. You, the employer, may owe the employer portion of payroll taxes on that now-taxable income.

This gets messy fast. If you discover the failure in March of the following year—after W-2s are already filed—you're filing corrected W-2s and explaining to your executives why their tax bill just went up.

The other consequence: if the failure is severe or recurring, the IRS can disqualify the entire plan. That almost never happens on a first offense, but it's the nuclear option if you ignore repeated failures.

How to Fix a Failed Test

You have two paths, depending on when you catch it.

Fix It Mid-Year

If you run a mid-year projection and see that you're heading for a failure, you can adjust. Common fixes:

• Increase non-HCE participation. Run an enrollment campaign. Make the plan easier to understand. If people don't know what an FSA is or think it's risky, they won't elect it, and your concentration test suffers.
• Cap HCE elections. Some plans set a lower FSA contribution limit for highly compensated employees. That keeps their share of total benefits down. The IRS allows this as a fix.
• Expand eligibility. If part-timers were excluded and that's driving the eligibility test failure, lower the hours threshold and let them in.

The trap: you can't take benefits away from non-highly compensated employees to fix a test. The fix has to expand access or limit the top, not squeeze the middle.

Fix It After Year-End

If you discover the failure after the plan year closes, your only option is to report the excess benefits as taxable income for the affected employees. You amend their W-2s, they pay the tax, and you document the failure and the correction for your records.

Then you fix the plan design for the next year so it doesn't happen again.

When Testing Happens

You're required to test annually, and the testing looks back at the prior plan year. Most employers test in the first quarter of the new year, after the prior year's payroll data is final.

Some employers test mid-year as a projection to catch problems early. That's not required, but it's smart if you're a small business with a few high earners and uneven participation. Fixing a projected failure in July is easier than unwinding a completed failure in February.

Why Small Employers Fail More Often

The math works against you when the denominator is small. In a 200-person company, even if executives max out their FSA elections and most line staff skip it, the concentration test might still pass because the raw number of non-key employees is large enough to dilute the key employees' share.

In a 12-person company, three owners maxing out their elections and seven employees skipping the FSA means the owners' share is enormous. You fail the concentration test almost by default unless participation is near-universal.

The other factor: small employers are more likely to run premium-only plans with no FSA or dependent care option. A POP with low participation among non-owners is a guaranteed concentration test failure if the owners are paying significant premiums pre-tax.

What to Demand from Your Payroll Provider

Most payroll providers offer nondiscrimination testing as an add-on service. Some include it automatically if you're running a Section 125 plan through their system. Either way, you want:

• Annual testing reports showing all three tests and whether you passed.
• Mid-year projections if you ask for them.
• Clear identification of who counts as highly compensated, key employees, and the groups used for each test.

If your payroll company says "we handle compliance," ask explicitly whether that includes nondiscrimination testing. It doesn't always. And if they're only testing eligibility and benefits but skipping concentration, you're not actually compliant.

What Your Plan Document Should Say

Your Section 125 plan document has to include language stating that the plan will comply with nondiscrimination testing requirements. It should also describe how you'll handle failures—typically, by reporting excess benefits as taxable income to the affected employees.

If your plan was drafted from a template years ago and you've never updated it, the nondiscrimination language might be vague or missing. Get it reviewed. The IRS can disqualify a plan that doesn't address testing in the document, even if you've been testing in practice.

FAQ

Do I have to test if I only offer a premium-only plan?

Yes. A premium-only plan is still a Section 125 cafeteria plan, and all three nondiscrimination tests apply. POPs often fail the concentration test because participation among lower-paid employees tends to be lower—if they're on a spouse's plan or buying coverage elsewhere, they're not using the POP, and that skews the key employee percentage upward.

What happens if I didn't know I had to test and I haven't tested in years?

You're technically out of compliance for every year you didn't test. The IRS could disqualify the plan retroactively, but that's rare on a first discovery. Most employers in this situation start testing immediately, document the results going forward, and fix any current-year failures. If you're worried about prior years, talk to a benefits attorney or a CPA who handles cafeteria plan compliance. Voluntary correction programs exist.

Can I just exclude highly compensated employees from the plan to avoid testing?

You can, but it defeats the purpose. If no highly compensated employees participate, you don't have a discrimination problem—but you also don't have a plan that works for the people who typically drive adoption. Most employers want their executives in the plan because those are the employees who understand the value and actually use the benefits. A plan with no HCE participation often ends up with low overall participation, which makes the plan less valuable and harder to justify administratively.

How do I know if I passed without hiring someone?

If your payroll provider isn't running the test, you can calculate it manually. For the concentration test: total up all pre-tax benefit elections for the year (premiums, FSA contributions, dependent care, HSA employer contributions if run through the cafeteria plan). Split that total into key employees and everyone else. Divide the key employee total by the grand total. If the result is over 25%, you failed. The eligibility and benefits tests require reviewing your plan document and comparing your HCE group to your non-HCE group—doable, but more interpretive. Most employers pay someone to run it rather than risk getting the classification wrong.

Running the Plan Right

Nondiscrimination testing isn't optional, and it isn't a formality. It's the compliance gate that keeps your Section 125 plan's tax advantages intact. Employers fail these tests more often than the benefits industry likes to admit, especially small businesses where ownership is concentrated and participation is uneven.

Test annually. Catch failures early. Fix them by expanding participation or capping the top, not by squeezing the middle. And if your payroll company says they "handle everything," ask them point-blank whether nondiscrimination testing is included. It's not always, and the IRS doesn't care whose job you thought it was.

Running the plan, not just using it? The setup guide at /services/section-125-setup walks through the plan document, payroll setup, testing requirements, and the two traps that catch almost everyone—in plain English.