Personal Finance

More companies are offering an after-tax 401(k) option to big savers. Here’s how to use it

Key Points
  • If you reach the 401(k) employee deferral limit with money to spare, it may be possible to save more with after-tax contributions.
  • You can use the money for a Roth conversion, possibly saving on future taxes.
  • Some 21% of company plans offered after-tax 401(k) contributions in 2021, up from 19% in 2020, according to Vanguard. 
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Maxing out your 401(k) isn't easy, but if you reach the limit with money to spare, there may be a way to save more. 

In 2022, employees can defer $20,500 plus $6,500 for investors 50 and older. However, after-tax contributions may bypass those caps up to $61,000, including company matches, profit sharing and other plan deposits. 

While most plans still don't have the feature, the numbers have been creeping higher. Some 21% of company plans offered after-tax 401(k) contributions in 2021, up from 19% in 2020, according to Vanguard

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You can use the funds for the so-called mega-backdoor Roth maneuver — paying levies on earnings and moving the money to a Roth individual retirement account — for future tax-free growth. 

An estimated 14% of employees maxed out 401(k) plans in 2021, according to Vanguard, and 10% of workers with access to after-tax 401(k) contributions participated.

"It can be a really, really powerful technique for the right individual," said certified financial planner Dan Galli, owner at Daniel J. Galli & Associates in Norwell, Massachusetts.

If they're young enough and have years of tax-free growth ahead of them, it could be a game-changer.
JoAnn May
financial planner at Forest Asset Management

By rolling the money into a Roth IRA, investors may start building a tax-free pot of money for retirement, without rules to take the money out at a certain age.

"If they're young enough and have years of tax-free growth ahead of them, it could be a game-changer," said JoAnn May, a CFP and CPA with Forest Asset Management in Berwyn, Illinois.

After-tax vs. Roth accounts

It's easy to confuse after-tax 401(k) contributions with a Roth 401(k) account since both allow you to save money after taxes, but there are key differences.

For 2022, employees under age 50 may defer up to $20,500 of their salary into their company's regular pretax or Roth (after-tax) 401(k) account.

However, you can make additional after-tax contributions to your traditional 401(k), which allows you to save more than the $20,500 cap.

Navigating inflation requires a diversified portfolio
Navigating inflation requires a diversified portfolio

For example, if you defer $20,500 and your employer kicks in $8,000 for matches and profit-sharing, you may save another $32,500 before hitting the $61,000 plan limit for 2022.

The other twist is how earnings are taxed. While Roth 401(k) withdrawals (including earnings growth) are tax-free in retirement, any earnings on those "bonus" amounts added to traditional 401(k) plans are taxed.

"That's why it's important to get [after-tax contributions] out of the 401(k) plan periodically," May said.

Once per year, her clients withdraw after-tax contributions and earnings and roll the money into a pretax or Roth IRA. The downside of the Roth IRA option is there may be a tax bill on growth at the conversion.

Plans with after-tax 401(k) contributions may not educate employees about the option. In some cases, advisors may discover the feature buried deep within a client's benefits paperwork.

"The most important thing is to read your employee benefits handbook and pass it on to your advisor," said May.

Tax-free income

Whether someone leverages after-tax or Roth contributions, tax-free money may be valuable in retirement, Galli said.

When clients apply for Social Security, their portfolio income may hurt those benefits. Retirees may pay income taxes on up to 50% to 85% of their Social Security payments, depending on their modified adjusted gross income.

About 40% of those who receive Social Security income pay taxes on their benefits, according to the Social Security Administration.

Some retirees may also pay more for Medicare premiums. While most retirees don't pay for Medicare Part A, the base price for Medicare Part B starts at $170.10 for 2022.

Depending on their income, retirees may have to pay more for Medicare Part B, with top earners paying monthly premiums of $578.30.