On Investing: Accounts, Index Funds and Fees for Long Horizons

Investing for a long horizon comes down to a few decisions you make rarely and then leave alone: which accounts to use, what to hold inside them, and how much you pay in fees. Picking individual winners is not among them. For goals 15 or more years away, the order in which you fill tax-advantaged accounts and the cost of the funds inside them usually matter more than any single purchase.

Which accounts to fill, and in what order

Tax-advantaged accounts come with annual limits, and for 2026 the IRS has set them as follows.¹

A common order: contribute enough to a workplace plan to get the full employer match, then fund an IRA, then go back and raise workplace contributions, and only then use a taxable brokerage account. The choice between traditional (tax break now) and Roth (tax-free later) depends mainly on whether you expect your tax rate to be higher now or in retirement. Most people cannot know that, which is why holding some of each is a reasonable hedge.

Some 401(k) plans allow after-tax contributions above the $24,500 employee limit, which can then be moved into Roth money. Whether that works depends entirely on your plan's features. The guide to after-tax 401(k) contributions and the mega backdoor Roth explains the limit math and the plan features you need to check before trying it.

What an index fund is, as a category

An index fund is a mutual fund or exchange-traded fund that holds the securities in a market index, such as a broad US stock index, instead of a manager's picks. Two properties make the category useful for long horizons: broad diversification in a single holding, and generally lower costs, because no one is paid to research and trade individual stocks.

Index funds are not risk-free. A total-market fund falls when the market falls. What they remove is the risk that your particular fund manager underperforms the market you meant to own. This site does not rank funds or name products; the category and its trade-offs are what matter here.

Fees are the return you are guaranteed to lose

Fees come out every year whether returns are good or bad, and they compound. The SEC's investor bulletin shows a $100,000 portfolio growing 4% a year for 20 years. With a 0.25% annual fee it ends at about $208,000; with a 1% fee, about $179,000.² That three-quarter-point difference costs close to $30,000.

Look for three costs: the fund's expense ratio, any advisory fee charged as a percentage of assets, and any sales load or account fee. An advisory fee sits on top of fund costs. Example: a 1% advisory fee on a portfolio of funds charging 0.5% adds up to 1.5% a year. Advice can be worth paying for. Know the total first.

Understanding risk is where knowledge is thinnest

In the 2026 TIAA Institute–GFLEC Personal Finance Index, only 36% of questions about risk were answered correctly, the lowest of any area and low across every generation.³ Women scored 6 percentage points lower than men overall.³

The practical side of risk for long horizons fits in a few points. Diversification reduces the damage any one company or sector can do. Stocks have historically been volatile in the short run, so money needed within a few years usually belongs in cash or bonds. And the risk most long-horizon investors underestimate is their own reaction: selling after a fall locks in the loss. Choose an allocation you could hold through a large drop, then rebalance on a schedule rather than on headlines.

Related sections

Investing works best after the personal finance foundations are in place, especially an emergency fund. To see how a portfolio turns into a target number, read financial independence. For drawing the money back out, including the first years of withdrawals, see early retirement.