Guide
Max Out Your 401(k) as Young as You Can
Compound growth rewards time far more than it rewards effort. Money you invest at 25 has forty years to work; the same dollar at 45 has twenty. That difference isn't twice as good — it's about five times as good, and no amount of later diligence can buy the years back. If there is one financial decision where being early beats being clever, this is it.
What "maxing out" means in 2026
For 2026 the IRS lets you contribute $24,500 of your own salary to a 401(k), up from $23,500 in 2025. If you're 50 or older you can add a catch-up contribution of $8,000, for a total of $32,500. There's a larger catch-up of $11,250 available for ages 60 through 63. Employer contributions sit on top of these limits — the cap is on what comes out of your paycheck.
Most people can't hit $24,500 in their twenties, and that's fine. "Max out as young as you can" is a direction, not an entry requirement. Contributing something, early, and raising it a percentage point whenever you get a raise, gets you most of the benefit without ever feeling like a sacrifice.
The ten years you can't buy back
Here's the whole argument in one comparison. Assume $500 a month and a 7% average annual return.
Start at 25 and stop at 65: you contribute $240,000 and end with about $1,312,000. Start at 35 instead: you contribute $180,000 and end with about $610,000. The ten-year head start cost you $60,000 in contributions and returned roughly $702,000. Wait until 45 and the same $500 a month gets you to about $260,000.
Nothing about the later saver's behavior is worse. They contribute the same amount monthly, choose the same investments, show the same discipline. They're simply missing the decade when compounding does its heaviest lifting — because the growth in the final years is calculated on a balance that took decades to build.
And if you can max out: $24,500 a year from 25 to 65 at 7% lands somewhere near $5.4 million. From 35, about $2.5 million.
Start with the match
Before maxing anything, contribute at least enough to capture your full employer match. A 50% match is an immediate 50% return on that money, guaranteed, before a single dollar is invested. There is no other place in personal finance where that's available. Leaving a match uncollected is the most common and most expensive mistake in workplace retirement plans.
Check your plan documents for the vesting schedule too — some employers require a few years of service before their contributions are fully yours.
Why index funds and ETFs became the default
A 401(k) is a container, not an investment. What actually grows is whatever you hold inside it, and most plans offer a menu ranging from broad index funds to actively managed funds to target-date funds.
An index fund doesn't try to pick winners. It buys the whole index — every company in it, weighted by size — and accepts the market's return. An ETF is the same idea in a structure that trades like a stock. Neither is exotic; both are ordinary pooled investments whose appeal is what they don't do.
Two properties explain why they've become the standard recommendation for long-horizon investors. The first is diversification: owning hundreds of companies means no single failure can seriously damage you. The second is cost, and cost is the part people underestimate.
The fee you never see
Fund fees are quoted as an expense ratio and deducted automatically. You never write a check, which is exactly why they're easy to ignore.
Take someone maxing out at about $2,041 a month for forty years at a 7% return. In a fund charging 0.03%, they finish with roughly $5,312,000. In one charging 0.75% — not an outrageous fee for an actively managed fund — they finish with about $4,351,000. The difference is close to $961,000, for identical contributions and identical market performance.
Your plan is required to disclose these. Find the expense ratio for every fund on your menu; the number is usually smaller and the effect usually larger than people assume.
What "7% average" does and doesn't mean
Every projection above uses 7%, which is roughly the long-run average of a broad US stock index after inflation. Two honest caveats.
First, the average is not the experience. Markets deliver something like a 10% nominal average over long periods, but almost never in any given year. There are years down 20% or more, and stretches of several years going nowhere. The average is what emerges from decades of that volatility, not a rate you earn steadily.
Second, past performance genuinely does not guarantee future results. The historical record is the best evidence available for what long-horizon investing has done. It is not a promise about the next forty years.
Which is really an argument for the same conclusion: a long time horizon is what lets you ride out volatility, and a young investor has the most of it. Time in the market is the advantage — and it's the one advantage that only ever gets smaller.
If you can't max out yet
Almost nobody starts at the limit. What works is automation and small increases you don't have to think about. Contribute enough to get the full match today. Then raise your contribution by one percentage point every time you get a raise — you'll never feel money you never took home. Many plans offer automatic annual escalation that does this for you.
Getting to the limit at 32 instead of 25 still leaves you decades ahead of someone who waits for a convenient moment. The convenient moment does not arrive; the years leave regardless.
A necessary note. This article is general education, not financial, tax, or investment advice, and nothing here is a recommendation to buy or sell any security or to take any particular course of action. It doesn't account for your income, tax situation, risk tolerance, time horizon, debts, or plan's specific options. Investing involves risk, including possible loss of principal. Before making decisions about your retirement plan, talk to a qualified financial professional who can look at your whole picture.