How to Choose Index Funds in Your 401(k)

The 401(k) Advantage

A 401(k) is an employer-sponsored retirement account that provides significant tax advantages. Traditional 401(k) contributions reduce your taxable income today; Roth 401(k) contributions grow tax-free. In 2026, you can contribute up to $23,500 per year ($31,000 if 50 or older).

Always contribute at least enough to get your full employer match — it's an immediate 50–100% return on your money before any market returns.

Finding Index Funds in Your 401(k)

Not all 401(k) plans are equal. Some offer excellent low-cost index funds; others are loaded with high-fee active funds. Log into your 401(k) portal and look for funds with these characteristics:

• Expense ratio below 0.20% (ideally below 0.10%)
• Fund name includes "Index," "S&P 500," "Total Market," or tracks a major benchmark
• Managed by Vanguard, Fidelity, BlackRock (iShares), or Schwab

Building a Simple 401(k) Portfolio

If your plan offers good options, a simple two or three-fund approach works well:

• Option 1 (Simplest): Target-date index fund (e.g., "2055 Target Date Index Fund") — automatically adjusts allocation as you approach retirement.
• Option 2 (DIY): U.S. Stock Index Fund + International Stock Index Fund + Bond Index Fund in proportions appropriate for your age.

What If My 401(k) Has No Good Index Funds?

If your plan only offers high-cost actively managed funds, contribute enough to get the full employer match, then prioritize your Roth IRA for low-cost index fund investing. After maxing the Roth IRA, return to the 401(k) for additional contributions — the tax advantages still outweigh the higher fees in most cases.