A benefits director walks you through her tiered premium-sharing model. Lower-wage employees pay 10% of the health plan cost. Mid-level staff pay 20%. Highly paid executives pay 30%. Her team is proud of it, and on its face the design points the right direction. Executives carry more of the cost, frontline workers carry less, and the ACA affordability math gets easier.
Ask when she last ran a Section 125 contributions and benefits test on that structure, and the answer tends to be the same. The 401(k) gets tested every year. The affordability safe harbors get checked. The broker said they were fine.
Sometimes they are. The problem is that no one can prove it, because the one test that matters for a tiered contribution design gets skipped. A structure that tilts cost toward executives is directionally safe. The danger sits in the artifacts: the edge case where a part-time worker ends up paying more than an executive for the same coverage, buried in the arithmetic of hours-based tiers, spousal surcharges, or wellness incentives.
The logic that gets you into trouble
Tiered premium contributions are appealing because you want your lowest-paid employees to use the health plan rather than waive it when the payroll deduction hurts. You also want to avoid the ACA employer mandate penalties by keeping coverage affordable. Charging people based on what they earn feels fair, and in a tight labor market it doubles as a retention tool.
But making those deductions pre-tax is not a given. It's a privilege granted by Section 125 of the Internal Revenue Code, and that section carries its own nondiscrimination tests, separate from the ACA and separate from 401(k) ADP/ACP testing. The one that catches tiered designs is the contributions and benefits test in Prop. Treas. Reg. §1.125-7(c), one of three tests in the 2007 proposed regulations. The IRS never finalized those rules, but employers may rely on them in good faith, and they remain the operating standard for cafeteria plan testing.
How the trap actually works
The rule says a cafeteria plan cannot discriminate in favor of highly compensated participants as to contributions and benefits for a plan year. Most people read that and think, “My executives pay more, so I'm fine.” That logic is sound but incomplete. The test does not stop at the obvious design where an executive gets a richer subsidy. It compares the qualified benefits elected, and the employer contributions allocable to those benefits, between highly compensated participants and everyone else. Salary reductions count as employer contributions for this purpose.
The examiner weighs the entire contribution architecture. If any path lets a highly compensated participant end up with a more favorable contribution rate than a non-highly compensated participant for the same coverage, whether in dollars or as a share of premium, the plan can fail. That path does not have to be deliberate. It can be an artifact of how the benefits administration system calculates contributions when variables like part-time hours, wellness incentives, or spousal surcharges collide.
A contribution formula can intersect with hours-based coverage levels so that a part-time non-highly compensated employee pays a higher dollar amount for employee-only coverage than a full-time highly compensated employee. No one designs that on purpose. To an examiner, the side effect reads as a discounted benefit option for a highly compensated employee, and a pattern like that puts the plan's tax-favored status at risk.
The penalty is narrower than consultants often describe. If the plan fails the contributions and benefits test, the affected highly compensated participants and key employees lose pre-tax treatment for the plan year, and their elected benefit amounts become taxable income. Non-highly compensated employees keep their pre-tax status in full. The employer is left with W-2 corrections, tax withholding catch-up for those executives, and difficult conversations.
Section 105(h): the second test on a self-funded plan
If your medical plan is self-funded, the cafeteria plan tests are only the first layer. Self-funded plans carry a separate nondiscrimination requirement under Section 105(h), and Section 105(h) defines highly compensated individuals differently from Section 125. A contribution tier that passes one test can still trip the other. The penalty differs, too: a Section 105(h) failure can't be corrected after the fact, and the discriminatory benefits become taxable income to the affected highly compensated individuals.
There is a cascade risk as well. When self-funded benefits run through a Section 125 plan, a Section 105(h) failure can drag down the cafeteria plan treatment for those same highly compensated employees. If you run variable contributions on a self-funded plan, run both tests, not the cafeteria plan review alone.
Your benefits admin platform isn't the safety net you think it is
Modern benefits administration systems handle tiered contribution rates without complaint. You create employee classes by salary band or job level, assign employer subsidies, and the system calculates the rest. It feels solid because it is automated and the numbers balance every payroll cycle.
But few platforms proactively run a Section 125 contributions and benefits test against those custom tiers. The system flags ACA affordability problems and tracks eligibility. It won't tap you on the shoulder to say that your contribution design may have just undercut your cafeteria plan's tax status. That testing is usually a separate end-of-year manual process, if it happens at all, and by then a missed edge case is already locked into the plan year.
How to keep the equity without the exposure
You don't have to kill the tiered structure. You have to build it from the plan document out and test before the plan year closes. Four moves get you there.
- Ground tiers in broad, objective business classifications, not raw salary numbers. Use job band, hourly versus salary, or full-time status. Then document why those classifications do not hand highly compensated participants a better contribution rate than everyone else.
- Make sure no highly compensated employee pays a lower dollar amount than any non-highly compensated employee for identical coverage. The cleanest design keeps the employer subsidy equal or richer as you move down the pay scale, so highly compensated employees consistently pay equal or more in both dollar and percentage terms.
- Put the contribution methodology in the plan document, not in the benefits admin portal. The document is the legal foundation. The system configuration should mirror it exactly, and the configuration should be locked so it cannot change during open enrollment without legal review.
- Test early, not at year-end. Once open enrollment data settles, run a simulated nondiscrimination test. If your broker or TPA cannot do it, find someone who can. A failure caught before the plan year closes can often be corrected; one discovered in an audit cannot.
The bigger shift already underway
Section 125 exposure is one reason organizations have moved toward Individual Coverage Health Reimbursement Arrangements (ICHRAs). When you give employees a fixed allowance to buy their own coverage, premium sharing sits outside the employer group plan, which removes the cafeteria plan testing layer. But an ICHRA doesn't get a clean pass: it falls under the Section 105(h) nondiscrimination rules and the same-terms requirement within each employee class, unless the HRA reimburses only individual health insurance premiums. That is a different test burden, and the testing does not disappear. For some organizations the trade is still worth it. For others, a traditional group plan with a proper tier structure is simpler than the ICHRA administration.
For the rest still running a traditional group plan with variable contributions: find the cafeteria plan document, and pull the latest nondiscrimination testing results. If you can't show a clean pass on the contributions and benefits test, the problem only compounds.
This article is for general information only and is not legal, tax, or medical advice. Employers should consult their own advisors.