What’s Old Is New Again: “Mega Back Door” Roth IRA Contributions Spark New Interest in Old School After-Tax Contributions Blog Feature
Holly Roussel-Godfrey

By: Holly Roussel-Godfrey on May 24th, 2016

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What’s Old Is New Again: “Mega Back Door” Roth IRA Contributions Spark New Interest in Old School After-Tax Contributions

Roth 401(k) | Plan Design

Ever hear of voluntary 401k contributions? If you are like most people, probably not. They are after-tax employee contributions like Roth deferrals, but subject to different ERISA rules. Voluntary contributions have been around decades longer than Roth deferrals, but are less popular – mostly because their earnings can’t be withdrawn tax-free at retirement like Roth deferrals.

This disadvantage was partially mitigated when the IRS released Notice 2014–54, which simplified the rules for splitting the pre-tax and after-tax portions of a 401k distribution. This guidance made it easier for 401k participants to roll voluntary contributions into a Roth IRA, where the money could then grow tax-free – just like Roth deferrals inside a 401k plan.

The new IRS guidance got a lot of people excited about making voluntary contributions to their 401k plan. Why? They are subject to a much higher annual contribution limit than Roth deferrals ($61,000 vs. $20,500 for 2022). By utilizing this higher limit, a retirement saver can pump additional after-tax contributions into their 401k plan and then roll them into a Roth IRA for tax-free growth.

Over the past year, this tax saving strategy received a good bit of coverage in the media - including the New York Times and Morningstar. However, most of the coverage has just focused on the awesomeness of making $58,000 in after-tax contributions and then growing them tax-free inside a Roth IRA. The limited applicability of the strategy was rarely explained. I would like to do that now.

High 401(k) Fees

The MEGA “back door” Roth IRA contribution!

Roth IRAs are subject to relatively low contribution limits, based on the income of the taxpayer. Rollovers from a 401k plan into a Roth IRA are a different story – they have no dollar or income restrictions. As such, these rollovers are often called a “back door” Roth IRA contribution.

Given the very high contribution limits attributable to voluntary contributions, their rollover has been coined a “mega back door” Roth IRA contribution.

A fit for your 401k plan? Probably not.

When the “mega back door” Roth IRA contribution started to receive media coverage, we began to hear from 401k sponsors interested in adding voluntary contributions to their plan. The problem? Voluntary contributions are rarely viable in 401k plans that benefit both Highly Compensated Employees (HCEs) and non-Highly Compensated Employees (non-HCEs). Why? The Average Contribution Percentage (ACP) test.

The ACP test compares the average contribution rate for plan HCEs to the non-HCE average. This test fails when the HCE average exceeds the non-HCE average by more than the legal limit. In a traditional (non-safe harbor) 401k plan, both employer matching and voluntary contributions are tested. In a safe harbor 401k plan, just voluntary contributions are (usually) tested.

Why are voluntary contributions a problem? Assuming a HCE makes a $58,000 voluntary contribution to their 401k plan, their minimum contribution rate (based on the $265,000 income cap applicable to the ACP test) would be 20%. A high contribution rate like that drags the HCE average upwards making the ACP test more difficult (if not impossible) to pass.

When the ACP test fails, the most common correction method is returning excess contributions to the HCEs that contributed the most until the HCE average drops enough to pass the test. In other words, the HCE that made the $58,000 voluntary contribution is probably going to get a big chunk of that money back in order to pass the ACP test.

Another problem - safe harbor 401k plans lose their top heavy test “free pass” when voluntary contributions are made. That could make additional top heavy minimum contributions to “non-key” employees necessary.

Bottom line, voluntary contributions are rarely worth the trouble when a 401k plan covers non-HCEs due to their impact to annual IRS testing.

Solo 401k plans are the best candidates

Owner-only (or “solo”) 401k plans are generally the best candidates for voluntary contributions. Why? With no common law employees, they automatically pass ACP and top heavy testing.

Look, I get it – the “mega back door” Roth IRA contribution is a pretty exciting strategy for those that can afford it. I mean, who doesn’t want the biggest possible tax-free nest egg at retirement? Unfortunately, most 401k plans can’t support the voluntary contributions necessary to make the strategy work.

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About Holly Roussel-Godfrey

Holly Roussel-Godfrey joined the Employee Benefits industry in 2005 as head of marketing and sales for ftwilliam.com, a plan document and government forms software provider. Holly was responsible for developing successful marketing and sales strategies for each of the company’s software modules. Because of her passion for customer service, Holly was selected to develop a highly effective training program for Third Party Administrators and Advisors after the company was acquired by Wolters Kluwer in 2009. As Vice President – Marketing & Sales for Employee Fiduciary, Holly is responsible for the sales team as well as all marketing initiatives for the company, including inbound marketing and social media. Holly earned her BS degree in Marketing from the University of Wisconsin – Milwaukee.