When I started investing, I only thought about what to buy. I picked whatever fund was in front of me and never asked what kind of account it sat in. That was a costly oversight, because the account decides how much of the growth you actually keep.
Money in a traditional 401(k) gets a tax break today and is taxed when it comes out. Money in a plain brokerage account gets taxed along the way: on dividends, on capital gains, on every rebalance. Over a 30-year horizon, that tax drag can cost you 0.5 to 1.5 percentage points of annual return, enough to shrink a $1 million portfolio by hundreds of thousands of dollars compared to the same fund in a tax-sheltered account.
Two more accounts take that idea even further: the HSA, which is never taxed if you spend it on medical bills, and the Roth, which taxes you once and never again. Once I saw the whole picture, I stopped treating my accounts as separate containers and started treating them as one coordinated system. Where every dollar goes across those accounts is what I call the account fill order.
The 401(k): The Easiest Starting Point
The 401(k) was the first account I took seriously because it requires almost no effort to begin. The money comes out of your paycheck before you see it, it lowers your taxable income today, and the employer match adds money you’d never get otherwise. The match is part of your compensation. Skipping it means working for less than you earn. A 401(k) normally lets you withdraw penalty-free starting at 59½.
I was slow to learn that lesson. My first full-time employer in the US offered a 401(k) from 2009, but I was focused on paying off my master’s loan and never contributed. I started in 2011, at my second employer. Even then, I put in too little to collect the whole match, leaving free money on the table for years.
Every employer structures the match differently. I’ve had plans that matched 50 percent of my first 6 percent and plans that matched 30 percent of everything I put in. Check your Summary Plan Description (your HR portal usually has it) or ask your benefits team directly. The number you need is the minimum contribution that captures every dollar your employer will give you.
From Small Contributions to the Maximum
In the early years, the maximum contribution felt impossible. First I was paying off student debt, then I was building an emergency fund. From 2015 I started raising my contribution by a point or two every time a raise came in, so the extra money reached my 401(k) before my lifestyle could adjust upward. That stealth increase got me to the maximum without feeling like I was sacrificing anything.
Running projections on how maxing out would compound over decades changed my goal from “contribute something” to “reach the maximum.” Any free compound-interest calculator will show you the difference. Plug in your current balance, your contribution rate, and a 7 percent average return, then compare maxing out to your current pace. The final push to the 401(k) max came in 2020. In 2026, the employee contribution limit is $24,500, with a total limit of $72,000 including employer contributions. These limits change most years. Check the latest IRS announcement before you set your contribution for the year.
Choosing Funds Inside Your Plan
Inside the plan, the fund choice matters as much as the contribution. Many plans include high-fee actively managed funds, and the difference in cost compounds against you for decades. Mine started in the plan's default, a high-fee target-date fund. Target-date funds shift from stocks to bonds as you approach retirement, which sounds reasonable, but the expense ratios are often steep, and I don’t hold bonds at all.
After the target-date fund, I went through a phase of guessing: looking at past returns, even using a third-party service that connected to my 401(k) and picked funds for me. None of it made sense until I understood index funds. Once I realized I could invest in a low-cost S&P 500 index fund inside my own plan, I moved everything there. Same paycheck, same plan, far less going to fees.
If your plan has no good low-cost option, take the full employer match and invest additional savings in a Roth IRA, through the backdoor if your income is too high, or a taxable account with better choices. Some plans also offer a self-directed brokerage window inside the 401(k) where you can access a wider range of ETFs and index funds. Check whether your plan has that option.
The Traditional IRA
For my first years of investing, the 401(k) was my only retirement account. I didn’t understand IRAs at all and didn’t open one until 2018, years after my first 401(k) contribution.
A traditional IRA gives you a tax deduction now, and you pay tax when you withdraw. The 2026 contribution limit is $7,500, with an additional $1,100 catch-up if you’re 50 or older. If you have a workplace plan and your income is above the phase-out range, you lose the deduction. In 2026, that range is $81,000 to $91,000 for single filers and $129,000 to $149,000 for married filing jointly. That’s where the backdoor Roth comes in. You contribute after-tax dollars to a traditional IRA and convert them to a Roth IRA.
You can also open a spousal IRA for a non-working spouse, giving your household another bucket of tax-advantaged space even on a single income. That extra $7,500 a year adds up fast when it compounds for decades.
Catch-Up Contributions and SECURE 2.0
Catch-up contributions matter most for people who start late or want a final push. At 50, you can contribute an extra $8,000 to your 401(k) and an extra $1,100 to your IRA on top of the regular 2026 limits.
SECURE 2.0 added a larger “super catch-up” for ages 60 to 63 in workplace plans: $11,250 on top of the regular limit. If your plan offers it, the total 401(k) limit for that age window hits $35,750. Starting in 2026, workers who earned more than $150,000 in the prior year must make their 401(k) catch-up contributions as Roth contributions. If your plan doesn’t offer a Roth 401(k) option, you may not be able to make catch-up contributions at all. Confirm with your plan administrator. The IRS final regulations on this rule have the full details.
I’m in my early 40s, so catch-up contributions are years away for me. But a friend in my FIRE community started investing at 48 after a health scare, and the catch-up years are where someone in that position can make up the most ground.
401(k) Loans: Borrowing from Your Future Self
Your plan may let you borrow from your 401(k) for things like a first home purchase. I used a 401(k) loan in 2015 and paid it back in about a year. It was the right call for us, and I’d use one again if the numbers made sense.
The downsides stack up. You pay interest on the loan, and even though it goes back into your own account, the money you borrowed isn’t in the market during that time. Any growth you miss is gone forever. Worse, most plans require full repayment if you leave the employer. If you can’t pay it back, the outstanding balance becomes a taxable distribution with penalties attached.
Even paid back in a year, mine cost me interest and some missed market growth. It was still worth it to us, and that’s the point: know the price before you borrow.
When you leave an employer, you’ll see options for your old 401(k): keep it there, roll it to your new employer’s plan, roll it to an IRA, or take a distribution. Never take a distribution. You’ll owe income tax plus a 10 percent penalty, and that money leaves the tax-advantaged system permanently. If you’re weighing a career move, the rollover decision is one of the financial details worth settling before you give notice.
Automate and Forget
My biggest mistakes were simple ones, and automation fixed them. Set up your contribution through payroll so you decide once. Never count that money as spendable income. Let it run whether the market is up or down. Every paycheck invests the same amount. That’s dollar-cost averaging, and it takes the timing question off the table entirely.
My point-or-two climb with every raise is the habit that matters most: raise the contribution before you feel the raise. It built more wealth than any stock pick I ever made.
For now, the 401(k) is where your investing starts. If your employer has a 403(b) instead of a 401(k) (common at non-profits and universities), the structure, limits, and tax treatment are the same.
Log into your payroll portal and check that your 401(k) contribution captures the full employer match. If it already does and you carry no debt above 7%, raise it by one percentage point.
The next account is the HSA, the one most people treat as a checking account for the doctor.
What You Need to Remember
- The account your money sits in determines how much growth you keep. Tax drag in a regular brokerage can cost 0.5 to 1.5 percentage points a year.
- The 2026 401(k) employee limit is $24,500, with catch-up amounts of $8,000 at age 50 and $11,250 for ages 60–63.
- Always contribute enough to capture the full employer match. Skipping it leaves part of your compensation behind.
- Look for the lowest-cost index fund in your plan instead of expensive target-date funds.
- Starting in 2026, high earners must make 401(k) catch-up contributions as Roth. Confirm your plan has a Roth option.
Questions I Always Get
Can I contribute to both a 401(k) and a traditional IRA in the same year? Yes, you can always contribute to both. The catch is that if you have a workplace plan and your income exceeds the phase-out range ($81,000 to $91,000 for single filers, $129,000 to $149,000 married filing jointly in 2026), you lose the IRA tax deduction. You can still contribute; you just won’t get the upfront tax break on the IRA side.
What happens to my 401(k) when I change jobs? You can leave it with your old employer, roll it into your new employer’s plan, or roll it into an IRA. Never cash it out. You’ll owe income tax plus a 10 percent penalty, and the money permanently leaves the tax-advantaged system. An IRA rollover usually gives you the widest fund selection, but rolling into your new employer’s plan keeps the backdoor Roth simple later, because pre-tax money sitting in an IRA makes part of every backdoor conversion taxable.
Should I take a loan from my 401(k)? Only after you run the numbers. The borrowed money misses market growth while it’s out, you pay interest, and most plans demand full repayment if you leave the employer. An unpaid balance becomes a taxable distribution with penalties. If the trade still makes sense after all that, as mine did, it can be the right tool.
What if my 401(k) only has high-fee funds? Contribute enough to capture the full employer match no matter what. The match is free money that outweighs any fee. Then direct additional savings to a Roth IRA (through the backdoor if your income is too high) or a taxable account where you pick the funds. Also check whether your plan has a self-directed brokerage window for access to low-cost index ETFs.
Does it matter which brokerage holds my 401(k)? Not as much as the funds inside it. The big providers all offer low-cost index funds, and the same strategy works on any of them. Focus on finding the cheapest S&P 500 or total market index fund your plan offers rather than worrying about the brokerage name on the account.