The 401(k) Trick That Lets Executives Contribute Up to $69,000 a Year

Your 401(k) plan may have a third contribution bucket that HR never mentioned. For some plans, the account accepts far more money each year than the standard employee deferral limit suggests. The mechanism is called the mega backdoor Roth, and for high earners between 50 and 65, it is one of the few remaining strategies that allow them to move large sums into permanently tax-free accounts under current law. However, this strategy is only available if your specific plan allows after-tax contributions and in-plan Roth conversions or in-service distributions, features present in about one-quarter of plans but more common at large employers

How the Three-Bucket System Actually Works

Every 401(k) operates under two separate IRS limits. The first governs how much you personally can defer from your paycheck: $24,500 in 2026 for employees under 50. The second, set under IRC Section 415(c), governs total annual additions to the plan from all sources combined. That ceiling rose from $70,000 to $72,000 in 2026.

The gap between those two numbers is where the mega backdoor Roth lives. The $72,000 total includes your employee deferral, your employer’s match, and a third category: after-tax (non-Roth) contributions. For a high earner receiving a $10,000 employer match, the available after-tax room is approximately $37,500. That money goes in after taxes, gets immediately converted to Roth inside the plan, and grows completely tax-free from that point forward.

Once converted, future gains are never taxed again, regardless of how large the account grows or what tax rates look like in 20 years.

The Plan Document Problem Nobody Warns You About

The strategy is perfectly legal, but your plan has to allow it. And HR departments rarely advertise the feature, even when it exists, so you have to look for it.

To confirm eligibility, pull your Summary Plan Description and search for two specific phrases. First, “after-tax contributions permitted.” Second, either “in-service withdrawals” or “in-plan Roth conversions.” Both must be present. If your plan lets you make after-tax contributions but lacks the conversion mechanism, you end up with money that grows tax-deferred, not tax-free. That means future gains get taxed at withdrawal, which is a meaningfully worse outcome.

So who actually offers this? Large employers, particularly in tech and financial services, are your best bet. About a quarter of plans offer it overall, but the numbers are much higher in those industries. Smaller employers, by contrast, frequently do not.

If your plan document is missing either phrase, here is something most people never think to try: ask your plan sponsor to amend the document. Some employers will add the feature when employees request it directly, especially if they want to stay competitive on benefits.

The SECURE 2.0 Layer That Compounds the Advantage

If you are between 60 and 63, SECURE 2.0 gives you a higher contribution limit. In 2026, the standard 401(k) deferral is $24,500 with a regular catch-up of $8,000 for anyone 50 or older. But if you are 60 to 63, you can add $11,250 instead, bringing your total employee deferral to $35,750.

From there, the total plan limit applies. The IRS caps all contributions to your 401(k) at $72,000 in 2026, including your deferrals, your employer’s match, and any after-tax money. For a 62-year-old with a $10,000 employer match who maxes out the super catch-up, roughly $26,000 of after-tax room remains. That after-tax money, when converted to Roth, becomes an annual Roth contribution that no income limit can block. If you earn enough to be phased out of direct Roth IRA contributions, the mega backdoor Roth is one of the few ways left to move significant money into tax-free accounts.

One new wrinkle for 2026: if your prior-year wages exceeded $150,000, your catch-up contributions must go into a Roth account. That means no upfront tax deduction, but the money grows tax-free from there. If your plan does not offer a Roth feature, you may not be able to make catch-up contributions. Either way, the after-tax conversion strategy remains available regardless of income.

The Legislative Risk You Cannot Ignore

Congress tried to kill this strategy in 2021, as the Build Back Better Act would have eliminated after-tax 401(k) contributions starting January 1, 2022. The bill failed in the Senate, so the mega backdoor Roth survived. But the message was clear: Congress views it as a high-earner tax break worth closing.

Any future budget reconciliation bill could revisit it. That risk applies to future contributions, not existing ones. Retroactively taxing already-converted Roth balances would face enormous political resistance. Converting now locks in your Roth balances as a hedge against the possibility that the window closes in a future Congress.

Three Steps to Take Before Your Next Paycheck

1. Request your plan’s Summary Plan Description from HR or your plan administrator. Search for two specific phrases: “after-tax contributions” and “in-plan Roth conversion.” If both appear, you have full access. If only one appears, you have partial access. After-tax contributions without the conversion mechanism leave you with money that grows tax-deferred only, meaning future gains remain taxable at withdrawal. If neither phrase appears, ask your plan sponsor whether a plan amendment is possible.
2. To determine your personal after-tax room, review your planned employee deferrals and your employer’s expected match against the $72,000 total plan limit. The remainder after accounting for those contributions represents your maximum after-tax contribution for the year. Adjust upward if you are between 60 and 63 and using the $11,250 super catch-up.
3. If your income exceeds the first IRMAA threshold ($109,000 for single filers in 2026), consult a fee-only advisor before executing large conversions. The conversion itself does not add to taxable income because after-tax contributions carry no pre-tax basis, but any earnings on those contributions since they were made will be taxable at conversion. Converting promptly after each contribution keeps that taxable earnings window as short as possible.