The Mega Backdoor Roth IRA and Other Ways to Maximize a 401(k)

Did you know: Numerous 401(k) retirement plans allow after-tax contributions. This creates financial planning opportunities that are frequently overlooked. Read this blog post for more information on maximizing your 401(k) plan.


The most popular workplace-sponsored retirement plan is far and away the 401(k) — a plan that can be both simple and complex at the same time. For some of your clients, it functions as a tax-deductible way to save for retirement. Others might see its intricacies as a way to maximize lifetime wealth, boost investments and minimize taxes. One such niche area of 401(k) planning is after-tax contributions, an often misunderstood and underutilized area of planning.

Before we jump into after-tax contributions, we need to cover the limits and the multiple ways your clients can invest money into 401(k) plans.

Employee Salary Deferrals and Roth

The most traditional way you can contribute money to a 401(k) is by tax-deductible salary deferrals. In 2019, employees can defer up to $19,000 a year. If they’re age 50 or older, they can contribute an additional $6,000 into the plan. In 2020, these numbers for “catch-up contributions” rise to $19,500 and $6,500 respectively.

Someone age 50 or over can put up to $25,000 into a 401(k) in 2019 and $26,000 in 2020 through tax-deductible salary deferrals. Additionally, the salary deferral limits could instead be used as a Roth contribution, but with the same limits. The biggest difference is that Roth contributions are after-tax. And as long as certain requirements are met, the distributions, including investment gains, come out income tax-free, whereas tax-deferred money is taxable upon distribution.

Employer Contributions

Employers often make contributions to a 401(k), with many matching contributions. For instance, if an employee contributes 6% of their salary (up to an annual indexed limit on salary of $280,000 in 2019 and $285,000 in 2020), the company might match 50%, 75%, or 100% of the amount. For example, if an employee earns $100,000 a year and puts in $6,000 and their employer matches 100%, they will also put in $6,000, and the employee will end up with $12,000 in their 401(k). Employers can also make non-elective and profit-sharing contributions.

Annual 401(k) Contribution Cap

Regardless of how money goes into the plan, any individual account has an annual cap that includes combined employee and employer contributions. For 2019, this limit is $56,000 (or $62,000 if the $6,000 catch-up contribution is used for those age 50 and over). For 2020, this limit rises to $57,000 ($63,500 if the $6,500 catch-up contribution is used for those age 50 and over).

Inability to Max Out Accounts

If you look at the limits and how people can contribute, you might quickly realize how hard it is to max out a 401(k). If a client takes the maximum salary deferral of $19,000 and an employer matches 100% (which is rare), your client would only contribute $38,000 into the 401(k) out of the maximum of $56,000. Their employer would need to contribute more money in order to max out.

Where After-Tax Contributions Fit In

Not all plans allow employees to make after-tax contributions. If the 401(k) did allow this type of contribution, someone could add more money to the plan in the previous example that otherwise maxed out at $38,000.

After-tax contributions don’t count against the salary deferral limit of $19,000, but they do count toward the annual cap of $56,000. After-tax contributions are what they sound like — it’s money that’s included into the taxable income after taxes are paid, so the money receives all the other benefits of the 401(k) like tax-deferred investment gains and creditor protections.

With after-tax contributions, clients can put their $19,000 salary deferral into the 401(k), get the $19,000 employer match, and then fill in the $18,000 gap to max out the account at $56,000.

Mega-Roth Opportunity

If the plan allows for in-service distributions of after-tax contributions and tracks after-tax contributions and investment gains in separate accounts from salary deferral and Roth money, there’s an opportunity to do annual planning for Roth IRAs.

Clients can convert after-tax contributions from a 401(k) plan into a Roth IRA, without having to pay additional taxes. If a plan allows in-service distributions of after-tax contributions, the money can be rolled over to a Roth IRA each year. However, it’s important to note that any investment gains on the after-tax amount would still be distributed pro rata and considered taxable. Earnings on after-tax money only receive tax-deferred treatment in a 401(k); they aren’t tax free.

Clients can roll over tens of thousands of dollars a year from a 401(k) to a Roth IRA if the plan is properly set up. They can even set up a plan in such a way so the entire $56,000 limit is after-tax money that’s distributed to a Roth IRA each year with minimal tax implications. This strategy is referred to as the Mega Backdoor Roth strategy.

Complexities Upon Distribution of After-Tax Contributions

What happens to after-tax contributions in a 401(k) upon distribution? This is a complex area where you can help clients understand the role of two factors:

  1. After-tax contributions are distributed pro-rata (proportional) between tax-deferred gain and the after-tax amounts.
  2. Pre-tax money is usually considered for rollover into a new 401(k) or IRA first, leaving the after-tax attributed second. The IRS provided guidance on allocation of after-tax amounts to rollovers in Notice 2014-54.

Best Practices for Rollovers

Help your clients navigate the world of rollovers with after-tax contributions by following best practices. If a client does a full distribution from a 401(k) at retirement or separation of service, they can roll the entire pre-tax amount to a new 401(k) or IRA and separate out the after-tax contributions to roll over into a Roth IRA. The IRS Notice 2014-54 previously mentioned also provides guidance for this scenario.

You can help your clients understand after-tax contributions by envisioning after-tax money in a 401(k) as the best of three worlds. These contributions enter after taxes and give your client tax-deferred money on investment growth, allow them to save more money in their 401(k) while also giving them the opportunity to roll it over into a Roth IRA at a later date.

After-tax contributions build numerous planning options and tax diversification into retirement plans. Before your clients allocate money toward after-tax contributions, it’s important they understand what their plan allows and how it fits into their overall retirement and financial planning picture.

SOURCE: Hopkins, J. (17 December 2019) "The Mega Backdoor Roth IRA and Other Ways to Maximize a 401(k)" (Web Blog Post). Retrieved from https://www.thinkadvisor.com/2019/12/17/the-mega-backdoor-roth-ira-and-other-ways-to-maximize-a-401k/