Think you maxed out your 401(k)? The real limit is actually almost $50,000 higher.
Most people think the 401(k) “max” is the annual amount you can send from your paycheck into the plan. For 2024, that employee deferral limit is $23,000 (plus a $7,500 catch-up if you’re 50 or older). But there’s a second, much larger cap that often flies under the radar: the total annual additions limit. In 2024, that cap is $69,000 per person, or $76,500 if you’re 50+ because catch-up contributions sit on top. That means the real ceiling can be roughly $46,000 higher than the deferral max—and even more if you’re eligible for catch-up contributions.
Here’s how it works and how to use it.
The two 401(k) limits people confuse
– The employee deferral limit (Internal Revenue Code Section 402(g)) is what you personally choose to contribute pre-tax or Roth from your paycheck. 2024 limit: $23,000, plus $7,500 catch-up at age 50+.
– The annual additions limit (Section 415(c)) is the all-in cap for everything that hits your account within the year. 2024 limit: $69,000, or $76,500 with catch-up. It includes:
– Your own pre-tax and Roth deferrals
– Employer matching contributions
– Employer profit-sharing contributions
– Your after-tax (non-Roth) employee contributions
– Any forfeitures your employer allocates to you
What does not count toward the 415(c) cap:
– Catch-up contributions (they’re on top)
– Rollovers from other plans
– Investment earnings
Why this matters
If you stop at $23,000, you might be leaving tens of thousands of dollars of tax-advantaged space unused. Between employer funding and your own after-tax contributions, many workers—especially those at companies with generous plans or anyone with a solo 401(k)—can fill much more.
The three paths to the bigger number
1) Employer match and profit sharing
– Employer dollars count toward the $69,000 total, not your $23,000 deferral limit.
– You can’t control the formula, but you can make sure you contribute enough to capture the full match.
– For business owners, “employer” profit-sharing can be up to 25% of W-2 wages (or roughly 20% of net self-employment income), subject to the overall cap and compensation limits.
2) After-tax employee contributions (not Roth)
– Some plans let you contribute after-tax dollars beyond your $23,000 deferral, up to the $69,000 annual additions limit.
– These are different from Roth deferrals. After-tax contributions go in after tax, but earnings grow tax-deferred. On their own, that’s not ideal—unless you use the “mega backdoor Roth.”
3) The mega backdoor Roth
– If your plan allows in-plan Roth conversions or in-service distributions, you can:
– Contribute after-tax dollars up to the 415(c) cap, then
– Convert those dollars to Roth (either inside the plan or to a Roth IRA).
– Done promptly, the conversion moves most of the money into Roth with little tax on earnings, giving you more Roth space than regular deferrals allow.
Concrete examples (2024 figures)
– Under age 50, large-plan example:
– You defer $23,000 (pre-tax or Roth).
– Employer match totals $6,000.
– That’s $29,000 so far. You could still add up to $40,000 in after-tax contributions to reach the $69,000 cap. If allowed, convert those after-tax dollars to Roth via mega backdoor.
– Age 50+, same setup:
– You defer $23,000 + $7,500 catch-up.
– Employer match $6,000.
– Your total excluding catch-up is $29,000. You can add up to $40,000 after-tax to reach $69,000—then the $7,500 catch-up sits on top for a total of $76,500.
– Solo 401(k), business owner (W-2 comp $200,000 via S-corp):
– Employee deferral: $23,000.
– Employer profit sharing: up to 25% of comp, but limited by the $69,000 cap. Here, you could add $46,000 of profit-sharing (23,000 + 46,000 = 69,000).
– If 50+, you can also add $7,500 catch-up for $76,500 total.
Important guardrails and gotchas
– Plan features vary. To do after-tax and mega backdoor Roth, your plan must allow after-tax contributions and either in-plan Roth conversions or in-service rollovers to a Roth IRA. Many large-company plans do; many don’t.
– Nondiscrimination testing can limit after-tax. After-tax employee contributions are subject to ACP testing. If you’re a highly compensated employee, your after-tax contributions may be curtailed or refunded.
– Compensation limits apply. Only the first $345,000 of compensation (2024) counts when calculating matches and profit sharing. Employer contributions are also limited to 25% of eligible compensation.
– One deferral limit across all jobs. If you change employers midyear, your combined pre-tax and Roth deferrals across all 401(k)/403(b) plans still can’t exceed $23,000 (2024). However, the annual additions limit generally applies per employer.
– Catch-up contributions are separate. They don’t count toward the $69,000 cap, but they must be pre-tax or Roth deferrals (not after-tax).
– Taxes on mega backdoor conversions. Converting after-tax contributions triggers ordinary income only on any earnings converted. Converting promptly minimizes earnings.
– Timing and payroll. After-tax contributions must flow through payroll before year-end. In-service rollovers or in-plan conversions may be allowed only at set intervals.
How to find your extra room
1) Read your Summary Plan Description or benefits site:
– Does the plan allow after-tax employee contributions?
– Does it allow in-plan Roth conversions or in-service rollovers?
– Is the plan safe harbor? (Helps with testing on deferrals, though after-tax still faces limits.)
2) Ask HR/benefits:
– What is the employer match/profit-sharing formula?
– Are there caps on after-tax contributions beyond IRS limits?
– How often can I convert or roll over after-tax contributions?
3) Map your path to the cap:
– Start with your $23,000 deferral (plus $7,500 if 50+).
– Add expected employer contributions.
– The difference up to $69,000 (2024) is potential after-tax space.
4) Automate and monitor:
– Turn on after-tax payroll contributions to fill remaining space.
– Schedule periodic in-plan conversions or in-service rollovers to Roth.
– Watch year-to-date totals, especially if your employer adds profit sharing late in the year—you don’t want to overshoot the 415(c) cap.
Why this can be a game changer
– More tax-advantaged space: Instead of stopping at $23,000, you might shelter up to $69,000 per year ($76,500 if 50+).
– Massive Roth expansion: The mega backdoor Roth can move tens of thousands into Roth annually, far beyond the regular IRA or Roth IRA limits.
– Faster retirement readiness: Filling this space for even a few years can materially change your retirement trajectory.
A quick note on other plans
– 403(b) plans follow similar limits, and some public-sector workers with a 457(b) plan have a separate deferral bucket there. But the strategy and availability depend on plan rules. Treat each plan’s specifics carefully.
Bottom line
Maxing your paycheck deferrals is only step one. The real 401(k) limit—what can land in your account in a single year—is far higher, thanks to employer contributions and, in the right plan, after-tax contributions you can convert to Roth. For 2024, that all-in cap is $69,000, or $76,500 if you’re 50 or older. Check your plan’s features, coordinate contributions, and consider using the mega backdoor Roth to capture the near-$50,000 of additional space most savers don’t realize is available.
Note: IRS limits adjust for inflation. Verify the current-year numbers before you act, and consider consulting a qualified tax or retirement professional for your situation.
