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Tax Planning

Mega Backdoor Roth: Turning After-Tax 401(k) Money Into Roth Savings

A mega backdoor Roth uses after-tax 401(k) contributions, then converts them to Roth; in 2026 the total plan cap is $72,000 before catch-ups.

Mega Backdoor Roth: Turning After-Tax 401(k) Money Into Roth Savings

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What is a mega backdoor Roth?

  • It's a way to move money into Roth status beyond the normal Roth 401(k) and Roth IRA limits, with no income limit.
  • You make after-tax (non-Roth) contributions to a 401(k), then convert them to Roth inside the plan or roll them to a Roth IRA.
  • It only works if your employer's plan allows both after-tax contributions and a way to convert or withdraw them while you're still employed.
  • Once converted, future growth can come out tax-free if the Roth holding and age requirements are met.
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Full Guide

What is a mega backdoor Roth?

  • It's a way to move money into Roth status beyond the normal Roth 401(k) and Roth IRA limits, with no income limit.
  • You make after-tax (non-Roth) contributions to a 401(k), then convert them to Roth inside the plan or roll them to a Roth IRA.
  • It only works if your employer's plan allows both after-tax contributions and a way to convert or withdraw them while you're still employed.
  • Once converted, future growth can come out tax-free if the Roth holding and age requirements are met.

How much room is there in 2026?

  • The overall limit on contributions to your account is $72,000 in 2026, covering your deferrals, employer contributions, and after-tax dollars combined.
  • Age-based catch-up contributions ($8,000 at 50+, or $11,250 at ages 60 to 63) sit on top of that limit.
  • Illustration: $24,500 of deferrals plus $9,000 of employer contributions leaves up to $38,500 for after-tax contributions.
  • The limit also can't exceed 100% of your pay, and many plans set a lower percentage cap on after-tax contributions.

Plan features required

  • An after-tax contribution source, separate from pre-tax and Roth deferrals, which many plans still don't offer.
  • Either in-plan Roth conversions or in-service withdrawals of after-tax money that can be rolled to a Roth IRA.
  • Nondiscrimination testing can force refunds of after-tax contributions for highly compensated employees if not enough others participate.
  • The summary plan description and your benefits portal usually spell out which features exist and how often conversions are allowed.

How is the conversion taxed?

  • After-tax contributions have already been taxed, so converting them adds no income, but any earnings before conversion are taxable.
  • Automatic or frequent conversions keep pre-conversion earnings small, which keeps the tax on them small.
  • IRS Notice 2014-54 lets you send the after-tax portion of a distribution to a Roth IRA and the pre-tax earnings to a traditional IRA.
  • Roth accounts carry five-year rules, and which clock applies depends on whether the money stays in the plan or moves to a Roth IRA.

How does it fit with other savings choices?

  • Unlike the backdoor Roth IRA ($7,500 in 2026), the mega backdoor isn't affected by the IRA pro-rata rule on existing pre-tax IRA balances.
  • Money in a 401(k) or Roth IRA is less accessible before 59½ than a taxable brokerage account, which matters with near-term goals.
  • The $24,500 deferral limit applies per person across all employers, while the $72,000 limit generally applies separately per unrelated employer.
  • Starting in 2026, catch-up contributions for employees with prior-year FICA wages above $150,000 must be made as Roth.

Risks that could limit the strategy

  • Employers can remove after-tax or in-service conversion features at any time through a plan amendment.
  • Congress has proposed ending after-tax conversions before, and future legislation could restrict them.
  • Leaving a job ends new contributions to that plan, so the strategy depends on each employer's plan design.

Key takeaways

  • The mega backdoor Roth depends entirely on plan features, so checking plan documents is the first step.
  • The 2026 room is $72,000 minus your deferrals and employer contributions, subject to plan caps and testing.
  • Converting soon after contributing keeps taxable earnings low.
  • This is educational only; confirm plan rules with your benefits administrator and tax treatment with a CPA.
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For 2026, you can defer $24,500 to a 401(k), plus $8,000 at 50+ or $11,250 at ages 60 to 63; total contributions from all sources cap at $72,000.

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