Yes, you can manage your own 401k, but the range of what “manage” means depends on the plan. In a standard employer plan you choose among a pre-selected menu of funds. If your plan offers a brokerage window, you can buy individual stocks and ETFs inside the account. And if you’re self-employed and sponsor a Solo 401k, you can act as your own trustee and direct the money almost anywhere the tax code allows. Each path has its own rules, costs, and limits.
Managing a Standard Employer Plan
Most workplace 401k plans are set up as participant-directed accounts under ERISA Section 404(c). The employer’s committee builds a menu of investment options, and you decide how to split your money across them. In exchange for that control, the plan sponsor is generally off the hook for the results of your choices. You’re not stuck with whatever the committee picked, but you’re also limited to what the committee picked.
A typical menu includes domestic stock funds, international equity funds, bond funds, and target-date funds that shift toward more conservative holdings as you approach retirement. To see exactly what’s on offer, request the Summary Plan Description from HR. That same document spells out how often you can change allocations and what fees you’ll pay.
Making changes is simple. Log into the plan administrator’s portal, review current holdings, and adjust the percentage going into each fund. You can change how new contributions get invested, rebalance the existing balance, or both. Most plans process the request at the end of the trading day based on each fund’s net asset value. Some charge short-term trading fees if you move money in and out of the same fund too quickly, so read the plan rules before swapping frequently.
Opening a Brokerage Window
Some employer plans offer a self-directed brokerage account, often called a brokerage window, that opens the investment universe well beyond the standard menu. Instead of choosing among 20 or 30 pre-selected funds, you can trade individual stocks, ETFs, and a wider range of mutual funds. If the feature is available, you’ll find the details in the plan document or fee disclosure.
Setup usually involves a supplemental application acknowledging that you’re taking on added responsibility for investment decisions. Once approved, you transfer money from the core plan balance into the brokerage side of the account. Trading then works much like any retail brokerage, with market or limit orders during trading hours.
The freedom isn’t unlimited. About 46% of plans with brokerage windows restrict certain investments.1DOL.gov. Understanding Brokerage Windows in Self-Directed Retirement Plans Common prohibitions include employer stock (to avoid concentration risk), over-the-counter bulletin board securities, and municipal bonds. Some plans also block options trading. Transaction fees and annual maintenance charges vary by provider, so weigh those costs against the value of the expanded access before moving a large balance.
Running a Solo 401k If You’re Self-Employed
If you run a business with no full-time employees other than yourself and your spouse, a Solo 401k gives you the broadest control over your retirement investments. You need an Employer Identification Number from the IRS and a written plan adoption agreement to get started.2Internal Revenue Service. One-Participant 401(k) Plans
The standout feature is checkbook control. As both the employer and the plan trustee, you open a bank or brokerage account in the plan’s name and direct investments yourself. You don’t need to call a custodian or wait for approval to buy an asset. Write a check or initiate a wire from the plan’s account, and the transaction is done. This structure supports investments that standard employer plans never touch, including real estate and private notes, within the legal limits described below.
Annual Filing Once You Cross $250,000
Once total plan assets reach $250,000 at year-end, you must file Form 5500-EZ with the IRS.2Internal Revenue Service. One-Participant 401(k) Plans The deadline is the last day of the seventh month after the plan year ends, which is July 31 for a calendar-year plan.3Internal Revenue Service. 2025 Instructions for Form 5500-EZ Missing the filing can trigger penalties. Plans below $250,000 in assets are exempt unless it’s the plan’s final year.
What You Still Can’t Do
More control brings stricter rules about what the plan can own and who it can transact with. Federal tax law imposes an excise tax of 15% of the amount involved for each year a prohibited transaction stays uncorrected. If it still isn’t fixed, the penalty jumps to 100%.4Office of the Law Revision Counsel. 26 USC 4975 – Tax on Prohibited Transactions The IRS actively enforces these rules, especially in Solo 401k plans where the owner has direct account access.
The core rule: your 401k cannot engage in transactions that benefit you personally, or certain people and entities connected to you, rather than the plan. Buying property from the plan, leasing plan-owned property for personal use, or lending plan money to yourself outside the formal loan rules all qualify. The circle of “disqualified persons” extends beyond you to your spouse, ancestors, descendants, their spouses, and any business entity you control by 50% or more.4Office of the Law Revision Counsel. 26 USC 4975 – Tax on Prohibited Transactions
Certain assets are also off the table. The IRS treats the purchase of a “collectible” with plan funds as an immediate taxable distribution equal to the cost of the item. Collectibles include artwork, rugs, antiques, stamps, coins (with limited exceptions), gems, and alcoholic beverages. Narrow exceptions exist for certain U.S. gold and silver coins and for bullion meeting specific fineness standards, but only if a bank or approved trustee holds physical possession.5Internal Revenue Service. Investments in Collectibles in Individually Directed Qualified Plan Accounts
Watching the Fees That Erode Returns
Every 401k charges fees, and they eat into returns whether the market goes up or down. The two main categories are investment fees (the expense ratio built into each fund) and administrative fees (recordkeeping, legal compliance, and account maintenance charged by the plan).
On the investment side, 401k participants paid an average expense ratio of about 0.31% on equity mutual funds in 2023, roughly 40% less than the average for all equity fund investors outside of employer plans. Target-date funds averaged around 0.30%. Those numbers have dropped sharply over the past two decades as index funds and institutional share classes have become standard in workplace plans.
Administrative costs are harder to pin down because plans structure them differently. Some charge a flat annual fee per participant, others deduct a percentage of assets, and some employers absorb part of the cost. Total all-in plan costs commonly run between 0.5% and 2% of assets depending on the plan’s size and the funds offered. A plan with $10 million in assets almost always charges more per participant than one with $500 million. On a $200,000 balance, the difference between a 0.5% and 1.5% all-in fee is $2,000 a year.
2026 Contribution Limits
How much you put in is arguably the most important decision you control. For 2026, you can defer up to $24,500 of your salary on a pre-tax or Roth basis.6Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500 Once employer contributions (matching or profit-sharing) are added in, the combined total cannot exceed $72,000.7Internal Revenue Service. Notice 2025-67: 2026 Amounts Relating to Retirement Plans and IRAs
Catch-up contributions give older workers extra room. At age 50 and older, you can add $8,000, for a total employee deferral of $32,500.7Internal Revenue Service. Notice 2025-67: 2026 Amounts Relating to Retirement Plans and IRAs Between ages 60 and 63, an enhanced catch-up of $11,250 applies instead, bringing the maximum employee deferral to $35,750.6Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500
A SECURE 2.0 wrinkle takes effect in 2026. If your FICA-taxable wages from the sponsoring employer exceeded $150,000 in 2025, any catch-up contributions you make must go into a Roth 401k account. If the plan doesn’t offer a Roth option, you cannot make catch-up contributions at all.
Solo 401k limits follow the same employee ceiling. You can also contribute up to 25% of your net self-employment income as the employer’s profit-sharing contribution, within the same $72,000 combined cap (or $80,000 with the standard catch-up at age 50, or $83,250 with the enhanced catch-up at ages 60 through 63).7Internal Revenue Service. Notice 2025-67: 2026 Amounts Relating to Retirement Plans and IRAs
Rolling Over to an IRA After You Leave a Job
When you leave an employer, rolling your balance into a Traditional or Roth IRA gives you the widest investment freedom. You’re no longer limited to the employer’s fund menu or even a brokerage window’s restricted list. An IRA lets you trade stocks, bonds, ETFs, and mutual funds, and in some cases alternative investments, without employer-imposed limits.
Request a direct rollover so the old plan sends the money straight to your new IRA custodian. If the check is made payable to you instead, the plan must withhold 20% for federal taxes, and you’ll need to replace that amount out of pocket within 60 days or the withheld portion becomes a taxable distribution.8Office of the Law Revision Counsel. 26 USC 3405 – Special Rules for Pensions, Annuities, and Certain Other Deferred Income
The Creditor Protection Tradeoff
ERISA-qualified 401k plans carry an anti-alienation provision that makes them essentially untouchable by creditors in bankruptcy, with no dollar cap. IRAs do not get the same treatment. In federal bankruptcy, IRA assets are protected only up to approximately $1,711,975, a figure adjusted for inflation every three years. Outside of bankruptcy, protection varies by state and may be significantly weaker.
If you have substantial assets or work in a profession with high liability exposure, keeping money in an employer 401k, including a former employer’s plan when they allow it, may protect you better than rolling into an IRA. The investment flexibility of an IRA is real, and so is this gap in legal protection.