Should you add $30,000 to your retirement with an after-tax auto Roth conversion?

That opens a window to make a strategic move with after-tax contributions that you can then immediately use to do a backdoor conversion into a Roth account within your retirement plan. 

The benefit of making after-tax contributions, generally, is to avoid paying tax on the growth until you withdraw the money in retirement, otherwise, you could just keep the money in your pay and put it in a taxable brokerage account. If you move that money to a Roth account, however, you won’t incur tax on the growth at all. In addition, the Roth account will not be subject to required minimum distributions when you are retired. 

Say, for instance, you’re 55 years old and you make $200,000. If you contribute your maximum with the catch-up and your employer adds a 6% matching contribution, which would be $12,000, you’re only using up $42,000 of the $73,500 allowed. You could add up to $31,500 in after-tax dollars this year if your employer allows that as a plan feature. Depending on how your administrator works, you’d likely make this election in the same place you choose how much you contribute to your 401(k). Setting up the automatic transfer to a Roth account would likely take a phone call, however. 

“We saw a 126% increase in participation from 2021 to 2022,” says Nathan Voris, director of investments, insights and consultant services at Schwab Retirement Plan Services. “People are starting to see it, starting to understand it.”

How after-tax Roth conversions work

To make use of this strategy, your employer plan has to offer both the feature to make after-tax contributions and the ability to do in-plan conversions to Roth. About 25% of plans that Vanguard handles offer this combination, and about 4% of participants with access have converted assets, says Maria Bruno, head of U.S. wealth planning research at Vanguard. 

With both features activated, it makes saving extra money kind of seamless. You get paid and taxes are taken out, then the after-tax dollars you designate as a contribution are moved directly to your retirement account. On the back end, the administrator sweeps the account and moves the money into a Roth “bucket” before it has a chance to accrue any taxable growth. 

“As soon as money is invested, it’s converted, so you’re not triggering tax,” says Bruno. “It’s very attractive, because you’re converting what would be taxable growth to tax-free growth, which is kind of unique. You’re also creating tax diversification.”

Your retirement account probably contains many such buckets, whether you realize it or not. Some administrators will break down the categories of sources for you to see on your account summary. You might have one for your main traditional 401(k) contribution and one for your employer’s matching contribution, plus perhaps another bucket if your plan offers a Roth 401(k) option. 

The reason the administrator keeps these separated is that different contributions have different limits, vesting schedules and rules governing how you withdraw. 

“That’s a day-to-day function of a record-keeper,” says Voris. 

When you should consider the option

Your salary is going to be the biggest factor of whether you can make use of this retirement plan feature. After-tax contributions will only come into play if you’ve already reached the limit of employee contributions, which only 14% of participants do, according to Vanguard. 

If you have the ability to save more, then after-tax conversions to Roth are appealing. “If you’re maxing out and you’re looking to add several thousand dollars, it has a real impact. The story sort of tells itself. This is a pretty darn good way to do it,” says Voris. 

If you’re not quite at that salary level, but you’re still interested in moving as much money into a Roth account as possible, there are ways you can start doing that now. The easiest way is to just put money directly into a Roth IRA. If you are under the IRS income limit—under $138,000 for singles, or $218,000 for marrieds for the full amount—you can contribute $6,500 in 2023, or $7,500 if you’re 50 or older. (Note: You can make IRA contributions for 2022 up until your tax filing deadline, but the limits for 2022 are slightly lower, $6,000 and $7,000 with catch-up.)

If your workplace plan offers a Roth 401(k) option—which some 77% of plans do, according to Vanguard—you can put in all of your $22,500 or whatever portion you wish. Doing steady contributions like this during your working years will save you from having to think about Roth conversions down the road. 

But not everyone is interested in paying more in taxes now. Roth 401(k)s lag traditional contributions significantly, with only 15% participation. “Behaviorally people want the tax-deferment right away, it’s immediate gratification,” says Bruno. 

There’s also a level of uncertainty as to whether it’s better for you to pay tax now or pay it later, because people don’t know whether they will be in a higher or lower tax bracket in retirement when the money starts coming out. For that matter, the age for required minimum distributions keeps changing—it’s now 73, but will be 75 in 10 years. 

“It’s tricky in peak earning years. There’s some math to be done there, to see if it makes sense to do it,” says Bruno. 

Got a question about the mechanics of investing, how it fits into your overall financial plan and what strategies can help you make the most out of your money? You can write me at [email protected]. 

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