After the IRS Notice (2014-54), a participant can now specifically direct the pretax and after-tax amounts of any distributions or conversions without the limitation of having to take a proration of pretax and after-tax amounts.
Recent articles on the subject point out that a participant could potentially deposit substantial after-tax contributions above the individual deferral limit of $18,000 (for 2015). The after-tax contributions would be limited only by the Section 415 annual addition limit of $53,000 (or $59,000 for those over age 50). This 415 limit includes all contributions to the plan including pretax deferrals, Roth deferrals, after-tax contributions, and all employer contributions.
This could mean significant savings and future tax advantages for the participant. If the plan allows for in-service withdrawals or in-plan Roth distributions, employees could then choose to annually distribute the after-tax contributions to a Roth account, thus sheltering any earnings on the contribution from further taxation, instead of letting the earnings continue to grow inside the pretax account to be later subject to taxation upon withdrawal.
This sounds fantastic for the participant, but it feels too good to be true. What is missing? What isn t being considered? How do these potentially large contributions affect the plan?
As a compliance manager, I believe that the largest missing component in this discussion is the nondiscrimination testing. Some articles I've seen on the topic mention nondiscrimination testing, and some don t. But even when they do, it's an afterthought. All 401(k) plans are subject to some form of testing.
Where might large after-tax contributions make testing difficult?
It stands to reason that the participants with the ability to take advantage and be most interested in making additional large after-tax contributions would be highly compensated employees (HCEs). Whether an HCE because of compensation or because of ownership and attribution (such as the spouse of an owner not needing the wages), this is the group most likely to be able to fund these contributions.
Many 401(k) plans need to be tested for nondiscrimination of the average deferral rate (ADR) and average contribution rate (ACR) of HCEs as compared with the ADR and ACR rates of non-highly compensated employees (NHCEs). They are referred to as the 401(k) ADP and 401(m) ACP tests. The 401(k) ADP test assesses pretax and Roth contributions, while the 401(m) ACP test looks at the employer matching contributions and employee after-tax contributions.
Let's work an example. If it is true that the participants who will likely take advantage will be the HCEs, these larger after-tax contributions could negatively affect the results of the ACP test.
Let's consider a 401(k) plan with a matching contribution rate equal to 100% of 4% of deferrals, with no additional employer contributions. In the plan, there is an HCE, age 47, who makes the maximum annual compensation and defers up to the maximum 402(g) limit. That participant will receive the maximum match of 4% of pay. Her account and testing rate would look like this:
| Ms. HCE | Compensation | Deferral | Match | Annual Additions | ACR |
| Original | $265,000 | $18,000 | $10,600 | $28,600 | 4.00% |
This participant is aware of the after-tax advantages and decides to make additional after-tax contributions up to the maximum annual additions limit. The HCE deposits an additional $24,400 of after-tax contributions. This is great and gets that participant the advantages of additional funding described above.
But remember when we said the ACP test examines the average of the HCEs rates against the average of the NHCEs rates? And that the ACP test includes both the employer match and after-tax contributions?
| Ms. HCE | Compensation | Deferral | Match | After-Tax | Annual Additions | ACR |
| Original | $265,000 | $18,000 | $10,600 | $28,600 | 4.00% | |
| With After-tax | $265,000 | $18,000 | $10,600 | $24,400 | $53,000 | 13.21% |
This participant just went from a 4% ACR to a 13% ACR. That is a significant jump.
For the sake of the example, let's assume that the NHCE ACP rate is 4%. That means that all eligible employees contribute enough to receive the max match—unlikely but easy for the example.
| Sample NHCE ACP Rate | 4% |
| Max HCE ACP Rate | 6% |
| Actual HCE ACP Rate | 13.21% |
| Potential Refund: | $19,100 |
**The restrictions of the ACP test are that the HCE ACP cannot be more than the lesser of two times or 2%+ the NHCE ACP rate.
Even with large plans with many HCEs, a few large rates can drastically change the HCE ACP rate.
Alternatively, let's assume that the above plan is a safe harbor 401(k) plan that satisfies the ACP safe harbor. Normally, this plan wouldn't even have to run the ACP test as it would be deemed to pass, which is due to the safe harbor. However, the after-tax contributions would still need to be tested. The mechanics of that test could include the ACP match or could test the after-tax on its own.
While it isn't a given the tests will not pass, it is important to consider the possibilities of failure and the impact this could have on the overall plan. It won t benefit the HCE to contribute these after-tax funds if they can't be retained because of testing failures.