Is a 401(k) an ERISA Plan? Default Rule and Solo Exceptions

If you work for a private-sector employer and contribute to a 401(k) at work, your plan is almost certainly an ERISA plan. The Employee Retirement Income Security Act of 1974 covers retirement plans that a private employer or union voluntarily establishes for its workers, and a 401(k) offered by any company with at least one common-law employee falls inside that coverage.¹² The three exceptions are solo 401(k) plans covering only a business owner (and possibly a spouse), plans sponsored by federal, state, or local government employers, and certain church plans.

The Default Rule for Workplace 401(k)s

Company size does not matter. A three-person LLC with a 401(k) has the same ERISA status as a Fortune 500 employer. Corporations, partnerships, sole proprietorships with staff, and union-administered retirement funds all sit inside the statute once a common-law employee is covered by the plan. If you receive a W-2 from a private employer and that employer offers you a 401(k), you can assume ERISA applies unless something specific tells you otherwise.

The 401(k) Plans That Fall Outside ERISA

Three categories are exempt from ERISA’s Title I framework:

Solo 401(k) plans that cover only the business owner, or the owner and their spouse. With no common-law employees in the plan, ERISA’s reporting, disclosure, and fiduciary rules do not apply. The IRS tax rules for 401(k)s still do.³
Government plans for federal, state, or local employees. These are explicitly excluded from ERISA and typically take the form of 457(b) or 403(b) plans in the public sector.⁴
Church plans maintained by churches or religious organizations, unless the organization voluntarily elects ERISA coverage.⁴

Solo 401(k) owners do carry one federal filing obligation, but it comes from the tax code, not ERISA: once total plan assets reach $250,000 at year-end, the owner must file Form 5500-EZ with the IRS.³

How to Confirm Your Plan’s Status

Two quick checks answer the question for a workplace plan:

Read your Summary Plan Description. Every ERISA plan must include a section titled “Statement of ERISA Rights” or “Your Rights Under ERISA.” If that section exists in the SPD, the plan is covered. If you never received an SPD, ask HR or the plan administrator — ERISA plans are required to give you one.⁵
Search the EFAST2 database at the Department of Labor website. It holds every Form 5500 filing. If your employer’s plan turns up, it is an ERISA plan filing under federal reporting rules.⁶

If you are a solo business owner asking about your own plan, the shortcut is simpler still: as long as no common-law employee is eligible to participate, your plan is not an ERISA plan.

What ERISA Coverage Actually Gives You

The label matters because ERISA plans carry federal protections that non-ERISA plans do not.

Protection From Creditors

Every ERISA pension plan must include an anti-alienation provision that keeps plan benefits from being assigned to or seized by someone else.⁷ Combined with ERISA’s preemption of state law, this generally puts money inside a workplace 401(k) out of reach of judgment creditors. The main exception is a Qualified Domestic Relations Order, which lets a court divide plan benefits in divorce or enforce child support.

In bankruptcy, the shield is even stronger. In Patterson v. Shumate, the Supreme Court held that ERISA’s anti-alienation clause qualifies as a restriction enforceable under nonbankruptcy law, which means the full balance of an ERISA 401(k) is excluded from the bankruptcy estate rather than merely exempt up to a cap.⁸

Solo 401(k) plans do not carry this federal anti-alienation shield. In bankruptcy, solo plan funds are still generally protected under federal bankruptcy exemptions. Outside of bankruptcy, protection depends on your state’s law, and coverage varies widely from full protection to limited protection with dollar caps.

Fiduciary Duties Owed to You

Anyone who manages an ERISA plan, controls its assets, or has discretion over its administration is a fiduciary and must act solely in the interest of participants under the prudent person rule.⁹ Fiduciaries must diversify plan investments, follow the written plan terms where consistent with ERISA, and avoid prohibited transactions with the employer and other parties in interest.¹⁰ A fiduciary who breaches these duties is personally liable to restore losses and return any improper profits, and can be removed by a court.¹¹ Non-ERISA plans do not carry these federal duties.

Required Disclosures

You are entitled to a Summary Plan Description that explains eligibility, benefit calculation, vesting, and the claims process in plain language, plus a Summary Annual Report each year giving a financial snapshot of the plan.⁵

If your plan lets you direct your own investments — nearly all 401(k)s do — the administrator must disclose administrative fees, individual transaction fees, and performance data for each investment option (average annual returns over 1, 5, and 10 years) before you first invest and at least annually after that.¹² When the plan temporarily suspends your ability to trade, borrow, or take distributions, you are entitled to a blackout notice at least 30 days before the suspension begins.¹³ Non-ERISA plans have no equivalent federal disclosure mandate.

A Structured Claims and Appeals Process

ERISA gives you defined deadlines when you file for benefits. The plan administrator has 90 days to decide your claim, with one 90-day extension allowed for special circumstances (you must be told about the extension within the original 90 days). If your claim is denied, you get at least 60 days to appeal — your SPD may give you more — and the plan then has 60 days to decide the appeal, with a possible 60-day extension.¹⁴

If the appeal is denied, ERISA gives you the right to sue in federal court to recover benefits, enforce plan terms, clarify future rights, or bring claims against fiduciaries for breach of duty.¹⁵ Without ERISA, a benefit dispute would run on state contract law, with remedies that vary by state.

When a Solo 401(k) Turns Into an ERISA Plan

A solo 401(k) loses its exemption the moment the business hires a common-law employee who becomes eligible for the plan. Eligibility follows the plan’s own terms within federal minimums: a plan can generally require an employee to be at least 21 and to complete one year of service with at least 1,000 hours.¹⁶

SECURE Act 2.0 added a second track. A long-term part-time employee who works at least 500 hours in each of two consecutive 12-month periods (and meets the plan’s age requirement) also qualifies for eligibility.¹⁷ Once any employee crosses the eligibility line, the plan is subject to ERISA’s full reporting, disclosure, fiduciary, and nondiscrimination rules, and the administrative cost profile changes accordingly.

1
U.S. Department of Labor. Employment Law Guide – Employee Benefit Plans
2
Office of the Law Revision Counsel. 29 USC 1003 – Coverage
3
Internal Revenue Service. One-Participant 401(k) Plans
4
Office of the Law Revision Counsel. 29 USC 1003 – Coverage
5
Internal Revenue Service. 401(k) Resource Guide – Plan Participants – Summary Plan Description
6
U.S. Department of Labor. Forms and Filing Instructions
7
Office of the Law Revision Counsel. 29 USC 1056 – Form and Payment of Benefits
8
Justia Law. Patterson v Shumate, 504 US 753 (1992)
9
Office of the Law Revision Counsel. 29 USC 1104 – Fiduciary Duties
10
Office of the Law Revision Counsel. 29 USC 1106 – Prohibited Transactions
11
Office of the Law Revision Counsel. 29 USC 1109 – Liability for Breach of Fiduciary Duty
12
eCFR. 29 CFR 2550.404a-5 – Fiduciary Requirements for Disclosure in Participant-Directed Individual Account Plans
13
eCFR. 29 CFR 2520.101-3 – Notice of Blackout Periods Under Individual Account Plans
14
U.S. Department of Labor. Filing a Claim for Your Retirement Benefits
15
Office of the Law Revision Counsel. 29 USC 1132 – Civil Enforcement
16
Fidelity Investments. Self-Employed 401(k) Plan Overview
17
Internal Revenue Service. Notice 2024-73