What Is a SIMPLE 401(k) and How Does It Work?

A SIMPLE 401(k) is a retirement plan designed for businesses with 100 or fewer employees that blends the light administrative feel of a SIMPLE IRA with the structural features of a regular 401(k), including participant loans and ERISA creditor protection. For 2026, employees can defer up to $17,000 of pre-tax pay, workers age 50 and older can add another $4,000 in catch-up contributions, and the employer must make either a matching or non-elective contribution every year. Congress created the plan through the Small Business Job Protection Act of 1996 and codified it at 26 U.S.C. § 401(k)(11), giving small employers a way to offer meaningful retirement benefits without the nondiscrimination testing that applies to a standard 401(k).¹

Which Employers Can Sponsor One

A business qualifies to sponsor a SIMPLE 401(k) if it employed no more than 100 people who each earned at least $5,000 during the prior calendar year. The count includes all employees across any commonly controlled businesses, so affiliated companies sharing ownership get aggregated. Part-time staff who earned below $5,000 don’t count toward the cap, but they might still be eligible to participate if they meet the individual eligibility rules.¹

The statute imposes an exclusive plan rule. A business sponsoring a SIMPLE 401(k) generally cannot maintain any other employer-sponsored retirement plan for its eligible employees during the same period. This is the trade-off for avoiding nondiscrimination testing. A company already running a traditional 401(k) or profit-sharing plan would need to terminate that plan before adopting a SIMPLE 401(k). If the business later grows past 100 qualifying employees, the IRS allows a two-year grace period to keep operating the plan while moving to a different structure.

Who Is Eligible to Participate

An employee becomes eligible if they earned at least $5,000 in compensation during any two preceding calendar years and are reasonably expected to earn at least $5,000 in the current year. Employers can loosen these requirements to let more workers in, but they cannot make eligibility more restrictive than the federal floor. A company could drop the two-year lookback to one year or lower the compensation threshold to $3,000, but could not raise the threshold to $7,000.²

Compensation for these purposes generally means the wages, tips, and other pay reported on the employee’s W-2, including salary deferrals. The $5,000 figure is set by statute and is not adjusted for inflation, so it has remained the same since the plan type was created.³

How Contributions Work

Mandatory Employer Contributions

Every SIMPLE 401(k) requires the employer to fund the plan, and this is one of the reasons the plan skips nondiscrimination testing. The employer picks one of two methods each year:²

A dollar-for-dollar match on employee deferrals, capped at 3% of that employee’s compensation. An employee who defers nothing gets no match.
A 2% non-elective contribution for every eligible employee, regardless of whether the employee defers anything.

The non-elective option often costs more because it covers the whole eligible workforce, but it simplifies the message to employees: the money lands in the account whether they participate or not. Either method produces a deductible business expense. For 2026, only the first $360,000 of each employee’s compensation counts when calculating employer contributions.⁴

Employee Deferral Limits for 2026

Employees can defer up to $17,000 of pre-tax pay for 2026, up from $16,500 in 2025. Workers age 50 and older can contribute an additional $4,000 in catch-up contributions, bringing their possible deferral to $21,000. Under SECURE 2.0, employees who are 60, 61, 62, or 63 during the year can use a higher catch-up of $5,250 instead of $4,000, pushing their ceiling to $22,250.⁵

SECURE 2.0 also created a higher tier of limits for the smallest employers. Companies with 25 or fewer eligible employees automatically get an $18,100 employee deferral cap for 2026 and a $3,850 age-50 catch-up. Employers with 26 to 100 eligible employees can opt into the higher limits, but only if they raise their employer contribution to a 4% match or a 3% non-elective contribution.⁵

Roth Contributions

SECURE 2.0 expanded Roth treatment for SIMPLE plans. Under Section 604 of the Act, a plan can now let employees designate employer matching and non-elective contributions as Roth, meaning those dollars go in after-tax and grow tax-free. Designated Roth employer contributions are included in the employee’s income for the year but are not subject to Social Security or Medicare withholding.⁶

Vesting, Withdrawals, and Rollovers

Every dollar in a SIMPLE 401(k) is 100% vested immediately. There is no graded schedule, no cliff, no waiting period. Whether the money came from the employee’s paycheck or the employer’s contribution, the worker owns it outright from day one. That’s a statutory requirement, not a plan design choice.¹

Withdrawals before age 59½ are subject to regular income tax plus a 10% early distribution penalty. Unlike a SIMPLE IRA, the SIMPLE 401(k) does not carry the harsher 25% early withdrawal penalty during the first two years of participation. That 25% rate is specific to SIMPLE IRA plans. Because the SIMPLE 401(k) is a qualified plan under the broader 401(k) framework, it follows the standard 10% penalty rules regardless of when the employee joined. The usual exceptions still apply: disability, certain medical expenses over a threshold percentage of adjusted gross income, substantially equal periodic payments, and the others listed in IRS guidance.⁷

Because a SIMPLE 401(k) is a qualified plan, a participant who leaves the company can roll a balance into a traditional IRA, a Roth IRA (with taxes owed on the conversion), or another employer’s 401(k) that accepts rollovers. There is no two-year waiting period like the one that restricts SIMPLE IRA transfers.

Loans and Hardship Withdrawals

A SIMPLE 401(k) can include a loan provision, which is a meaningful structural advantage over a SIMPLE IRA, where participant loans are prohibited entirely. If the plan document permits loans, the federal limits are the same as any other 401(k):⁸

The maximum loan is the lesser of 50% of the vested balance or $50,000.
Repayment generally runs five years, with payments at least quarterly. Loans used to buy a primary residence can stretch longer.
If repayments fall behind, the outstanding balance is treated as a taxable distribution and may trigger the 10% early withdrawal penalty.

Hardship withdrawals are also available if the plan allows them. IRS safe harbor rules recognize unreimbursed medical expenses, costs of buying a principal residence (excluding mortgage payments), post-secondary tuition and room and board, payments to prevent eviction or foreclosure, funeral expenses, and certain home repair costs from casualty damage.⁹

Unlike loans, hardship withdrawals are taxable income and may carry the 10% early distribution penalty if the participant is under 59½. They also cannot be repaid to the plan.

Setting Up and Running the Plan

A new SIMPLE 401(k) must be established between January 1 and October 1 of the year it takes effect. An employer that comes into existence after October 1 can set up the plan as soon as administratively feasible. This deadline exists to give employees enough time to make deferral elections before the calendar year ends.¹⁰

Unlike SIMPLE IRAs, which can be adopted using standardized IRS model forms, the SIMPLE 401(k) requires a formal plan document. Most employers adopt a prototype plan provided by the financial institution that will act as trustee. Custom-drafted documents are also permitted as long as they satisfy 26 U.S.C. § 401(k)(11). Getting the document right is where a third-party administrator or benefits attorney earns their fee.

Before each plan year’s 60-day election period, the employer must notify every eligible employee that they can start making salary deferrals or change an existing deferral amount. The notice must also state which employer contribution method the company has chosen for the coming year. For a new employee becoming eligible mid-year, the notice has to go out before the 60th day prior to their first day of eligibility.³

Because it’s a qualified plan under ERISA, a SIMPLE 401(k) carries compliance obligations a SIMPLE IRA avoids. Plans generally file Form 5500 or, for smaller plans, Form 5500-SF with the Department of Labor each year. One-participant plans file the simpler Form 5500-EZ, and plans with total assets under $250,000 at year-end are exempt from the filing requirement altogether. Anyone who exercises control over plan management or assets is a fiduciary under ERISA, which means acting solely in the interest of participants, investing prudently, diversifying to minimize the risk of large losses, and following the plan document. Personal liability attaches to fiduciaries who breach these duties.¹¹

ERISA also requires a fidelity bond for anyone who handles plan funds. The bond must cover at least 10% of the plan assets that person handled in the prior year, with a minimum of $1,000 and a maximum of $500,000, or $1,000,000 for plans holding employer securities. That’s separate from fiduciary liability insurance, which is optional.¹²

SIMPLE 401(k) Compared to a SIMPLE IRA

Both plans share the same 100-employee ceiling, the same mandatory employer contribution options (3% match or 2% non-elective), and the same base deferral limits. The differences are structural:

Participant loans are available in a SIMPLE 401(k) if the plan document allows them, and prohibited entirely in a SIMPLE IRA.⁸
A SIMPLE IRA imposes a 25% penalty on distributions taken within the first two years of participation. A SIMPLE 401(k) applies the standard 10% penalty from day one.⁷
SIMPLE IRA balances can only be transferred to another SIMPLE IRA during the first two years. SIMPLE 401(k) balances can roll into a traditional IRA or another qualified plan at any time after separation from service.¹³
Form 5500 is required for a SIMPLE 401(k) and not required for a SIMPLE IRA, which usually means hiring a third-party administrator.
SIMPLE 401(k) funds receive stronger federal creditor protection under ERISA. Protection for IRA-based plans varies by state.
A SIMPLE 401(k) follows qualified plan rules, so the employer can restrict in-service withdrawals. SIMPLE IRA participants can pull funds at any time, subject to taxes and penalties, because those accounts are individually owned.

For the smallest businesses that want minimal paperwork, a SIMPLE IRA is often easier. For an employer whose workforce values loan access, or an owner who wants tighter control over when distributions happen, the SIMPLE 401(k) is worth the additional compliance cost. Annual administration fees for a SIMPLE 401(k) typically run higher because of Form 5500 and the formal plan document, so the decision usually comes down to whether the extra features justify the extra overhead.

1
Office of the Law Revision Counsel. 26 U.S. Code 401 – Qualified Pension, Profit-Sharing, and Stock Bonus Plans
2
Internal Revenue Service. Choosing a Retirement Plan – SIMPLE 401(k) Plan
3
eCFR. 26 CFR 1.401(k)-4 – SIMPLE 401(k) Plan Requirements
4
Internal Revenue Service. Retirement Topics – 401(k) and Profit-Sharing Plan Contribution Limits
5
Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500
6
Internal Revenue Service. SECURE 2.0 Act Changes Affect How Businesses Complete Forms W-2
7
Internal Revenue Service. Retirement Topics – Exceptions to Tax on Early Distributions
8
Internal Revenue Service. Retirement Topics – Plan Loans
9
Internal Revenue Service. Retirement Topics – Hardship Distributions
10
Internal Revenue Service. Publication 560 (2025), Retirement Plans for Small Business
11
U.S. Department of Labor. Fiduciary Responsibilities
12
U.S. Department of Labor. Protect Your Employee Benefit Plan With an ERISA Fidelity Bond
13
Internal Revenue Service. SIMPLE IRA Withdrawal and Transfer Rules