The mega backdoor Roth is one of the few remaining ways to move a large sum of money into a Roth account in a single year. Despite the name, there is nothing exotic about it. It relies on a provision that has been in the tax code for decades, and the Internal Revenue Service has published guidance describing how the mechanics work. The obstacle is not the law. It is whether your employer’s retirement plan happens to offer the two features the strategy requires.
We work with households across the Sacramento region who are already contributing the maximum to a workplace plan and are looking for the next place to put savings. For a subset of them, this strategy is the answer. For many others, the plan document closes the door before the conversation starts. Knowing which group you fall into takes about ten minutes.
What the Mega Backdoor Roth Actually Is
Workplace retirement plans are governed by two separate dollar limits, and most savers are only aware of the first one.
The first limit caps what you may contribute out of your own paycheck as a pre-tax or Roth deferral. For 2026, the Internal Revenue Service set that figure at $24,500, up from $23,500 in 2025.
The second limit, found in Section 415(c) of the tax code, caps everything that lands in your account from every source in a year: your own deferrals, the employer match, profit sharing, and any after-tax contributions. For 2026 that ceiling is $72,000.
The space between those two numbers, minus whatever your employer contributes, is the opening. If the plan permits after-tax contributions, you may fill that space with dollars you have already paid tax on, and then convert those dollars to Roth. That two-step sequence is the whole strategy.
The 2026 Numbers Behind the Strategy
Consider a saver under age 50 whose employer contributes $10,000 in match and profit sharing:
| Total annual additions limit (2026) | $72,000 |
| Less employee deferral at the maximum | ($24,500) |
| Less employer match and profit sharing | ($10,000) |
| Remaining after-tax capacity | $37,500 |
Catch-up contributions sit outside the $72,000 figure. A saver age 50 or older may add $8,000 in catch-up for 2026, and a saver who turns 60, 61, 62, or 63 during the year may add $11,250 instead. The relevant cost-of-living adjustments are published annually and change the arithmetic each January.
Note that the employer contribution is the variable that matters most. A generous match shrinks the after-tax room. A plan with no match at all leaves the largest opening.
Two Plan Features Your Employer Must Offer
Neither of these is standard. Both must be present, and the plan document is the only authority.
1. After-tax contributions must be permitted. This is not the same thing as a Roth deferral, and the distinction confuses nearly everyone. A Roth deferral counts against the $24,500 limit. An after-tax contribution is a separate bucket that counts only against the $72,000 limit. Many payroll portals list them side by side with nearly identical names, so it is worth confirming with the plan administrator rather than guessing from a dropdown menu.
2. The plan must allow conversion of those dollars. This happens either through an in-plan Roth rollover, which moves the money into the plan’s Roth source, or through an in-service distribution that you roll to a Roth IRA. Internal Revenue Service guidance on rollovers of after-tax contributions confirms that after-tax amounts may be directed to a Roth IRA while the associated earnings are directed elsewhere.
The best plans convert automatically, every pay period. That matters because any investment earnings that accumulate on after-tax dollars before conversion are taxable when converted. Converting weekly leaves almost nothing to tax. Converting once a year after a strong market can produce a real bill.
Common Beliefs About the Mega Backdoor Roth
Four statements we hear regularly. Open each one to see whether it holds up.
“Congress eliminated the mega backdoor Roth a few years ago.”
“After-tax contributions count against my $24,500 deferral limit.”
“There is no income limit on this strategy.”
“If my plan allows Roth contributions, it allows this.”
How This Differs From the Ordinary Backdoor Roth
The two strategies share a name and almost nothing else.
The ordinary backdoor Roth happens inside an individual retirement account. You make a nondeductible traditional IRA contribution, capped at $7,500 for 2026, and convert it to Roth. Its main complication is the pro-rata rule, which measures the conversion against every traditional, SEP, and SIMPLE IRA you own and can make a supposedly tax-free conversion partially taxable.
The mega backdoor Roth happens inside the employer plan. The dollar amounts are several times larger, and the IRA pro-rata rule does not apply to the workplace plan balance. The tradeoff is that you control an IRA yourself, while the employer plan is controlled by someone else.
Where the Strategy Falls Short
Several groups will find this route closed, and it is better to learn that early.
- California public employees. The 403(b) and 457(b) plans common at school districts and state agencies rarely include an after-tax source. Governmental 457(b) plans operate under a different limit structure entirely and do not support this strategy.
- Plans that fail testing. After-tax contributions are subject to nondiscrimination testing. If highly compensated employees use the feature and other employees do not, the plan may be required to refund a portion of the contributions after year end.
- Households without real surplus. This strategy begins only after the $24,500 deferral is already funded. Directing $37,500 more into a retirement account requires cash flow that a great many households simply do not have, and an emergency reserve should come first.
- Savers who may need the money soon. Converted amounts follow Roth ordering and holding period rules. Money intended for a home purchase or a business launch in the next few years generally does not belong here.
One 2026 Change Worth Noting
Separately from this strategy, a new rule took effect on January 1, 2026. Under final regulations issued by Treasury and the Internal Revenue Service in November 2025, participants whose prior-year wages from the plan sponsor exceeded $150,000 must make any catch-up contributions on a Roth basis rather than pre-tax. If you are over 50, earning above that threshold, and have not reviewed your deferral elections since last year, that is worth a look regardless of whether the after-tax route is open to you.
What to Do Next
Start with one email to your plan administrator asking two questions: does the plan permit after-tax, non-Roth contributions, and does it permit in-plan Roth rollovers or in-service distributions. If both answers are yes, the next step is arithmetic: subtract your deferral and your expected employer contribution from $72,000 to find your capacity, then decide what portion of it your cash flow supports.
If you would like help deciding whether the mega backdoor Roth belongs in your plan for 2026, or you are not sure which retirement account should receive your next dollar, we are glad to talk it through. You may schedule a free 30-minute call with us at no cost and with no obligation.
Important Disclosures
The examples and figures in this article are educational and hypothetical. They do not constitute individualized investment, tax, or legal advice, and they are not a guarantee or projection of any particular outcome. Actual results vary with your circumstances, your plan document, and changes in tax law. Please consult a qualified financial, tax, or legal professional about your own situation. Rooney Wealth Management LLC is a California-registered investment adviser.
Rooney Wealth Management LLC is an investment adviser registered with the state of California. This article is for educational purposes only and is not tax, legal, or investment advice. Please consult your tax or financial professional regarding your specific situation.
