Mega Backdoor Roth


While many savvy investors know what a Backdoor Roth is, many are not familiar with the Mega Backdoor Roth. If you are a high-income earning business owner, the Mega Backdoor Roth feature can be a great option. The Mega Backdoor Roth is essentially the “After-Tax” contributions in a retirement plan, such as a 401(k) Profit Sharing Plan. After-Tax contributions are different from the commonly known Roth Deferrals in retirement plans. The MBR feature can be built into the plan document of a group or an individual plan.

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How Much Can a Participant Contribute to a Mega Backdoor Roth?

After-Tax contributions allow a participant to put up to $46,000 ($69,000 – $23,000 = $43,500) in 2024 into a Roth IRA, in addition to salary deferrals that can be either Pre-Tax or Roth. Below equation can be used to calculate how much a participant can contribute into his or her After-Tax portion in 2024:

$46,000 – Employer Match/NEC – Profit Sharing Contribution = After-Tax Contribution

How Does the Mega Backdoor Roth Work?

While it may sound simple, the Mega Backdoor Roth process can become complicated. After-Tax Contributions and In-Service Distributions must be built into the retirement plan document.

First, the participant would contribute up to the maximum allowed to the After-Tax Contributions bucket. Then, do an in-service withdrawal as a “rollover”. After-Tax Contributions can be rolled over to the Roth 401(k) Deferral account within the plan, or to participant’s own Roth IRA. There are tax implications to consider when choosing between your Roth 401(k) Deferral account and your Roth IRA. When it comes to withdrawal rules, Roth IRAs receive more favorable tax treatment than Roth 401(k) Deferral accounts. Please consult with your tax advisor regarding the tax implications.

Things to Consider When Adding a Mega Backdoor Roth to Your 401(k) Plan

The most important factor to be aware is that Mega Backdoor Roth plans will likely fail Actual Contribution Percentage (ACP) Tests, if the plan has Non-Highly Compensated Employees (NHCEs). Even offering NHCEs employer contributions may not pass testing. Even if it does, the amount Highly-Compensated Employees (HCEs) can contribute to the After-Tax (Mega Backdoor Roth) portion may be limited.

If you are a small business owner looking to create a retirement plan with a Mega Backdoor Roth feature, we highly recommend hiring a Third-Party Administrator (TPA) to administer the plan, as they can assist with contribution and deferral testing.

The bottom line is that retirement plans with the Mega Backdoor Roth option are best-suited for businesses where every (or most) employees are highly-compensated, or self-employed individuals and small business owners with no other full-time employees. Self-employed individuals with an Individual/Solo 401(k) plan can easily add a Mega Backdoor Roth option since they are generally not subject to any non-discrimination testing.