What does a retirement plan fiduciary have to do?
A legal duty, not a tax strategy
A fiduciary of an ERISA plan must act solely in the interest of participants and beneficiaries and with the care, skill, prudence, and diligence of a prudent person familiar with such matters (ERISA §404(a)(1), 29 U.S.C. §1104). ERISA §409 (29 U.S.C. §1109) makes a fiduciary who breaches those duties personally liable to restore the plan's losses. These rules protect participants; they do not reduce your taxes.
Reviewed by Ebot Mbi, CPA, EA · Last reviewed · Law and figures current as of September 17, 2026
Key takeaways
- The core duties are loyalty, prudence, diversification, and following the plan documents.
- Prudence is judged by the process you followed, so documentation is central.
- A breaching fiduciary can be personally liable to restore plan losses under ERISA §409.
- Plan sponsors, trustees, and committee members are often fiduciaries even if they do not think of themselves that way.
- ERISA Title I generally does not cover IRAs or plans that cover only owners and their spouses.
What it is
If you sponsor a 401(k), profit-sharing, or other employer retirement plan, someone must make decisions about investments, service providers, and fees. The people who exercise that discretion are fiduciaries under the Employee Retirement Income Security Act of 1974 (ERISA). Fiduciary status depends on what you do, not your title.
This page is not a tax strategy. It explains the legal standard that applies when you handle other people's retirement money, and why a documented process is your main protection.
Fiduciary exposure matters for small employers too. A business owner who picks the plan's investment menu, chooses the recordkeeper, or decides when payroll deferrals are sent to the plan is usually acting as a fiduciary for those decisions, even if an outside provider handles day-to-day administration.
What the law says
ERISA §404(a)(1) requires a fiduciary to discharge plan duties solely in the interest of participants and beneficiaries, for the exclusive purpose of providing benefits and paying reasonable plan expenses, with the care, skill, prudence, and diligence of a prudent person acting in a like capacity and familiar with such matters, by diversifying investments to minimize the risk of large losses, and in accordance with the plan documents.
ERISA §409(a) makes a fiduciary who breaches these duties personally liable to make good any losses to the plan resulting from the breach and to restore profits made through improper use of plan assets. The Department of Labor also enforces these duties and can assess civil penalties. Separately, IRC §4975 imposes excise taxes on prohibited transactions involving plans.
Requirements and tests
A prudent process usually includes the following:
- A written investment policy statement or equivalent criteria, applied consistently.
- Regular monitoring of fund performance, fees, and share classes against reasonable alternatives.
- Periodic benchmarking of recordkeeping and advisory fees, and review of required fee disclosures from service providers.
- Minutes or memos that record what was considered, what was decided, and why.
- Prompt deposit of employee deferrals, which are plan assets.
- Fidelity bond coverage for people who handle plan funds, as ERISA requires.
How it works
Courts generally ask whether the fiduciary used an appropriate process when the decision was made, not whether the result turned out well. A fund that underperforms is not by itself a breach; a fund chosen or kept without any comparison of cost or quality can be.
When a breach is proven, the fiduciary must restore the plan's losses from personal assets. Co-fiduciaries can also be liable if they knowingly participate in or enable another fiduciary's breach. Many sponsors reduce risk by appointing a committee, hiring advisers who accept fiduciary status, and buying fiduciary liability insurance, which is different from the required fidelity bond.
Delegation can reduce, but not remove, responsibility. If you appoint an investment manager that meets ERISA's requirements and acknowledges fiduciary status in writing, you are generally not liable for that manager's individual investment decisions, but you remain responsible for prudently selecting and monitoring the manager. Some plans also use a 3(38) investment manager or a 3(16) administrator to shift specific functions.
Assumptions: A 401(k) plan holds $2,000,000 in one fund; the balance is assumed to stay level for simplicity.; The plan's share class charges 0.95% a year; an otherwise identical share class of the same fund charges 0.45%.; No investment returns, contributions, or withdrawals are modeled.; Whether a court would find a breach, and the measure of any loss, depends on the facts and the process followed.
| Annual cost difference (0.50% × $2,000,000) | $10,000 |
|---|---|
| Cost difference over 5 years | $50,000 |
| Tax deduction created by the fiduciary duty | $0 |
An unreviewed 0.50% share-class difference costs participants about $10,000 a year in this example, which is the kind of loss §409 can require a fiduciary to restore.
Illustration only; not a projection of your results.
Risks and IRS scrutiny
Common problem areas include late deposit of employee deferrals, excessive fees, retail share classes when lower-cost classes of the same fund were available, and missing documentation of decisions. Late deposits can also create prohibited transactions reportable on Form 5330. The Department of Labor and private plaintiffs both bring claims, and the IRS reviews plan operations for tax qualification.
Fiduciaries who find a problem can often fix it through the Department of Labor's Voluntary Fiduciary Correction Program, and the IRS's Employee Plans Compliance Resolution System covers many operational errors. Correcting early usually costs less than defending a claim.
Who it is not for
If you are looking for a tax deduction, this page is not for you. It is also not a substitute for legal advice from ERISA counsel or investment advice from a registered adviser. It is for plan sponsors, trustees, and committee members who want to understand their exposure.
It is also not a substitute for an ERISA attorney's review of plan documents, service agreements, or claims, or for advice from a registered investment adviser on which funds to offer.
How ebotCPA helps
We review plan operations from the tax and compliance side, including deferral deposit timing, Form 5500 and Form 5330 reporting, and the documentation trail for fee decisions. Investment selection stays with your registered investment adviser. We coordinate with your attorney, who drafts the legal documents.
Book a $497 Case Analysis to have Ebot Mbi, CPA, EA review your facts before you act.
We coordinate with your attorney, who drafts the legal documents.
Frequently asked questions
Am I a fiduciary of my company's 401(k) plan?
If you have discretion over plan management, plan assets, or administration, you are likely a fiduciary under ERISA, whatever your title.
Can a fiduciary be personally liable for plan losses?
Yes. ERISA §409(a) makes a fiduciary who breaches a duty personally liable to make good the plan's resulting losses.
Does hiring a financial adviser remove my fiduciary duty?
No. You still have a duty to select and monitor the adviser prudently, although an adviser who accepts fiduciary status can share responsibility for investment decisions.
Does ERISA apply to my IRA or solo 401(k)?
ERISA Title I generally does not apply to IRAs or to plans that cover only business owners and their spouses, although the IRC §4975 prohibited transaction rules still apply.
Have facts like these?
Book a $497 Case Analysis to have Ebot Mbi, CPA, EA review your facts before you act.