Everyone Tells You to Max Your 401K. Nobody Tells You the Rest.
The liquidity trap and the $100,000 mistake hiding inside your retirement account.
A few years ago I sat down and looked at two numbers on a screen.
My retirement account balance. And my taxable account balance.
The retirement account balance was comfortable. The taxable account - the money I could actually access without penalty - was much smaller. Much smaller than I had realized until that exact moment.
It was during a bad stretch in the job market. People were getting laid off around us. My wife and I were fine, but nobody felt safe. And sitting there looking at those two numbers I had an uncomfortable realization.
If something went wrong - a job loss, a medical crisis, anything that disrupted income - I couldn’t touch the big number. Not without penalties, not without disrupting years of compounding that is the whole point of a retirement account. Not until I was 59½ - barring narrow exceptions like the Rule of 55 or 72(t) distributions, which come with their own constraints most people aren't positioned to use. The money we’d actually have to live on was the small number. The one I’d been neglecting for years.
I had been doing everything right. And somehow I had still gotten something important wrong.
The reason is embarrassingly simple in hindsight. Once I maxed my 401K every year, retirement felt handled. The rest was play money - money I had earned and was entitled to spend because the responsible thing was already done. The taxable account wasn’t a priority. It was whatever was left over after life happened.
What I hadn’t thought through carefully: if I ever needed to tap the retirement account early, “penalty” sounds abstract until you do the math. On a $50,000 withdrawal in the 35% tax bracket, you owe a 10% early withdrawal penalty plus ordinary income tax on the full amount. That’s roughly $22,500 gone before you see a dollar of it. And beyond the immediate cost - you’ve permanently interrupted years of compounding on money that can never go back in. The penalty is the small problem. The disrupted compounding is the real one.
I thought about this recently when I read a Wall Street Journal piece reporting that a record 6% of Vanguard 401(k) participants took hardship withdrawals in 2025, driven by financial strain from medical bills and housing costs - up from 4.8% in 2024 and pre-pandemic levels of around 2%. These aren’t people who planned to crack open their retirement accounts early. These are people who had no other choice. Because the big number was the only number they had.
This is what happens when your understanding of financial security is vague when it needs to be precise.
Most high earners think about financial security in terms of retirement. Max the 401K, let it compound, retire comfortably. That’s the plan. And it’s not wrong - it’s incomplete. Financial security isn’t only about retirement at 59½. It’s about having the right resources at the right time across your entire life - before 59½ and after it. The unexpected job loss at 48. The career change at 51. The early retirement you’ve been thinking about but haven’t fully modeled.
A large 401K balance feels like financial freedom. It isn’t. It’s financial freedom with a mandatory waiting period attached. And if you haven’t mapped your actual life plans against that waiting period - if you haven’t asked honestly what you’d live on between now and 59½ if something changed - then you don’t have a complete financial plan. You have a retirement plan. Those are not the same thing.
That realization sent me back to look more carefully at everything I thought I understood about my retirement accounts. That’s when I found the second thing I had gotten wrong. This one was more expensive.
For years I had maxed my 401K at the IRS pretax employee contribution limit - $23,500 in 2025 - and assumed I had done everything available to me. I knew vaguely that backdoor Roth existed. Friends had mentioned it. It sounded complicated and I filed it under things I’d look into someday.
Last year I finally got around to it. And while reading about backdoor Roth, something called mega backdoor Roth appeared. I had never heard of it. I looked into it. Then I did the math on what I had been missing.
Here’s what I hadn’t known: the $23,500 pretax limit is only one layer of the 401K. The total IRS limit across all contribution types in 2025 - your pretax contributions, your employer match, and after-tax contributions combined - is $70,000 ($77,500 for age 50+). If your employer’s plan allows after-tax contributions with an in-plan Roth conversion, you can contribute significantly beyond the $23,500 ceiling that most people think is the limit. That’s the mega backdoor Roth.
To be specific about what your plan needs to offer: first, the ability to make voluntary after-tax contributions above the standard employee deferral limit. Second, either in-plan Roth conversions - the ability to move those after-tax funds into a Roth account while still employed - or in-service distributions that allow the same. Both features need to be present. Not every plan offers them.
According to Vanguard’s How America Saves report, only 22% of Vanguard plans offered after-tax contributions in 2023. If your plan doesn’t have this option, you’re not alone - and you’re not out of options either. Regular backdoor Roth - contributing to a traditional IRA and converting to Roth - is available to most high earners regardless of employer plan and takes about twenty minutes to set up. It sounds complicated. It is not. If you haven’t done it, that’s where to start.
If your plan does offer the mega backdoor Roth and you haven’t been using it - the math on what you’ve left behind is worth calculating.
I had this option available in my own plan for five years without knowing it. Roughly $20,000 per year in additional tax-advantaged space I never used. That’s $100,000 in tax-advantaged contributions left on the table - not because the option didn’t exist, but because I never read carefully enough to know it did.
The part that still frustrates me: this information exists in your plan documents. It’s technically available. But nobody surfaces it for you proactively. You have to know what to look for before you can find it. Most people never do.
Here’s what made it worse: I called a few friends who had been doing regular backdoor Roth for years - people who considered themselves on top of this stuff - and none of them knew about the mega backdoor Roth option either. We were all operating on a vague understanding of something we thought we understood precisely.
Both of these mistakes came from the same place. Not ignorance - I knew 401Ks existed, I knew they had rules, I knew they had limits. I had a vague understanding. What I didn’t have was a precise one. And in personal finance, vague understanding has a specific dollar cost.
So two things worth doing this week.
First - think carefully about what financial security actually means for your life. Not retirement in the abstract. Your life specifically. When do you want to stop working? What would you do if your income disappeared tomorrow? Do you have enough in accessible accounts to support yourself through the gap years if your plans change? If you can’t answer those questions with specific numbers, the retirement balance is giving you a false sense of security.
Second - find your Summary Plan Description. It’s the document your employer is required to provide that explains exactly what your 401K plan offers. Read it carefully. Look specifically for “after-tax contributions” and “in-plan Roth conversion.” If those options exist and you haven’t been using them, you now know what that costs.
For a deeper dive on whether after-tax 401K contributions make sense for your specific situation, this Morningstar piece is worth reading: Should You Make Aftertax 401(k) Contributions? In-plan conversions are a no-brainer for heavy savers who have access to them.
The fine print in your retirement plan is not hiding. It’s sitting in a document you’ve never opened.
That’s where $100,000 went. Don’t let it happen to you.
I am not a financial advisor. Nothing in this newsletter is investment or tax advice. Please consult your CPA or tax advisor before making any financial decisions.
Fine Print Investing publishes weekly. If this made you open your plan documents - good. That’s exactly the point. Hit reply and tell me what you found.