At The Money: The Mega Backdoor Roth

Summary of At The Money: The Mega Backdoor Roth

by Bloomberg

16m•February 19, 2026
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Overview of At The Money

This episode of At The Money (host Barry Ritholtz) interviews Dan LaRosa, an expert on qualified retirement accounts, about the "mega backdoor Roth" — a way to get substantially more after‑tax dollars into Roth retirement vehicles through a 401(k) plan. The conversation explains how the strategy works, who can use it, plan/provider requirements, practical implementation, and key risks/limitations.

What is the Mega Backdoor Roth?

  • Basic idea: It lets participants contribute after‑tax dollars inside a 401(k) and convert those dollars to Roth treatment, dramatically increasing how much can be put into Roth‑type accounts versus standard Roth IRAs or Roth 401(k) deferrals.
  • Limits discussed in the episode: regular employee deferral (stated as $24,500) vs. a total all‑in plan limit up to $72,000 (this is the total contribution ceiling, including employer and after‑tax contributions).
  • Compared to a backdoor Roth IRA: traditional backdoor Roth IRAs are legal but limited (transcript example $7,500). The mega backdoor works on the same conversion principle but inside a 401(k) where limits are much higher.

How it works (technical outline)

  • Two plan features must be allowed by the employer/plan:
    1. After‑tax contributions to the 401(k).
    2. A way to move those after‑tax contributions into Roth — either:
      • In‑plan Roth conversions (after‑tax dollars converted to Roth and stay in the 401(k)), or
      • In‑service distributions rolled out to a Roth IRA.
  • Conversion cadence depends on the recordkeeper/provider:
    • Some plans offer daily automatic Roth sweeps/conversions (ideal).
    • Others allow only occasional manual conversions (once per year or limited times), which can be less tax‑efficient and harder to manage.

Who can — and should — use it

  • Good candidates:
    • High earners who’ve maxed regular 401(k) deferrals and want to save more tax‑free.
    • Employees of firms where enough people participate (so the plan won’t fail nondiscrimination/top‑heavy testing).
    • Solo practitioners/owner‑only 401(k) plans — these are especially well‑suited because there are no nondiscrimination tests for single‑owner plans.
    • Professions commonly using it: professional services (lawyers, accountants, advisors), many tech companies, doctors, and other high‑wage workplaces.
  • When it’s not practical:
    • Plans where only owners or the top wage earners would use it — that can fail compliance testing and make the feature unusable.
    • If present‑day liquidity is required (since in‑plan Roth funds generally follow Roth 401(k) distribution rules).

Plan/provider and employer roles

  • The plan sponsor/employer must modify plan documents to permit after‑tax contributions and conversion/distribution features. This is a plan‑level decision.
  • The recordkeeper/401(k) provider must be able to administer conversions (providers vary in functionality).
  • Custodians/brokers are less the gatekeepers than the plan design and recordkeeper capabilities.
  • No special tax gray area — IRS rules are clear that this is a legitimate strategy.

Practical considerations and limitations

  • Compliance testing: after‑tax features and conversions can trigger extra nondiscrimination/top‑heavy tests. If testing fails, the strategy may not be viable.
  • Administrative burden: there’s little to no direct cost to employees, but plan admins face extra complexity.
  • Provider variability:
    • Fidelity was singled out as having strong daily automatic conversion capability; other major providers (Schwab, Vanguard, etc.) have been improving but functionality varies.
    • Some providers limit the number/frequency of conversions per year — check before relying on annual conversion timing.
  • Liquidity and access: in‑plan Roth conversions follow Roth 401(k) rules (generally inaccessible until age 59½ or a distributable event). A taxable account may still make sense if you need current liquidity.
  • RMDs: per the transcript, SECURE 2.0 removed required minimum distributions (RMDs) from Roth 401(k)s (effective last year), which reduces a prior drawback of Roth‑401 treatment. (Follow up on current law changes for your specific situation.)

Best practices / Recommended steps (action checklist)

  • Check your plan documents or ask HR/plan sponsor whether the plan allows:
    • After‑tax contributions, and
    • In‑plan Roth conversions or in‑service rollovers to a Roth IRA.
  • Ask the recordkeeper/provider:
    • Do they support automatic/daily Roth sweeps?
    • Are there limits on the number of conversions per year?
  • If plan doesn’t offer it and it makes sense for many employees, raise it with HR/leadership — adoption is a plan‑level decision.
  • If self‑employed, consider an owner‑only (solo) 401(k) — the mega backdoor Roth can be especially effective there.
  • First time converting: work with your provider or financial/tax advisor to ensure correct execution and avoid tax mistakes.
  • Monitor nondiscrimination and testing implications if your firm has multiple employees.

Key takeaways / Notable quotes

  • “When it works and your plan allows it … it’s a cheat code.” — describes the outsized benefit of the strategy when available.
  • It is “completely legit” — not a loophole; the issue is plan design and administration, not IRS approval.
  • If your plan supports it and you can afford the extra contributions, Dan’s recommendation is generally: do it.

When a taxable account might be better

  • If you need immediate access to the money (liquidity).
  • If your employer’s plan doesn’t support frequent conversions or the plan likely fails compliance testing.
  • If administrative frictions mean the conversion timing results in tax inefficiency.

Summary: The mega backdoor Roth is a powerful, IRS‑blessed way to get substantially more money into Roth‑taxed retirement accounts when your 401(k) plan and provider support after‑tax contributions plus in‑plan conversions or in‑service rollovers. It’s especially attractive for high earners and solo business owners, but whether you can use it depends on plan design, nondiscrimination testing, and your recordkeeper’s capabilities. Check your plan documents and talk to HR/your 401(k) provider (and a tax/financial advisor) to see if you can implement it.