SIMPLE 401(k) Plan: How It Works and Why Almost No One Uses It

A SIMPLE 401(k) is a qualified 401(k) plan that follows the rules of a SIMPLE (Savings Incentive Match Plan for Employees) plan and applies to employers who have 100 or fewer employees. Because the SIMPLE plan has either mandatory 3% matching contributions or non elective 2% contributions as well as immediate vesting in 100%, it eliminates three other key requirements for an ADP (Actual Deferral Percentage), ACP (Actual Contribution Percentages) test and top heavy tests that are associated with a regular 401(k) plans. However, because of its deferral limits, almost no small business owner will select this option, given the lower deferral limit on this plan compared to the much higher limit found under 401(k).

It doesn't fit perfectly into either camp. It has legitimate 401(k) paperwork (e.g., an annual Form 5500), but allows employees to save no more than they could under a two-page SIMPLE IRA.

What is a SIMPLE 401(k) plan?

A SIMPLE 401(k) is a type of qualified retirement plan that incorporates the testing and administrative ease of the SIMPLE IRA with the formal legal structure of the 401(k). Like its cousin the SIMPLE IRA, it provides for an employer mandated contribution to each participant account. All employer contributions vest upon deposit. The primary distinction from a SIMPLE IRA is that instead of being deposited into an individual participants' IRAs, all employer contributions and employee deferrals are deposited into a 401(k) trust for administration, thereby requiring additional documentation requirements. Additionally, only employers having 100 or less eligible employees who earned at least $5,000 during the preceding year may establish this type of plan, and they cannot maintain another qualified plan at the same time.^[1]

Employees choose to postpone some of their earnings, and the employer will fund one of the two set SIMPLE formulas on top. In exchange for this required funding, this plan is considered to meet the ADP and ACP nondiscrimination testing requirements as well as the top-heavy testing requirements annually that a 401(k) must complete each year.^[3] Additionally, plans need to be created by October 1 in order to qualify under the current year's plan provisions. You are also responsible for providing an annual notice to your eligible employees with a 60 day time frame in which they can make elections.

What are the SIMPLE 401(k) contribution limits for 2026?

A SIMPLE 401(k) is an alternative that uses the SIMPLE elective-deferral limit, which is lower than the standard 401(k) limit. Under this type of plan, for 2026 an employee may elect to have contributions made up to $17,000 of their compensation deferred under the SIMPLE Plan. They are entitled to an additional $4,000 amount as a "catch-up" if they reach age 50 ($3,850 at businesses with 25 or fewer employees). There is a larger $5,250 "super catch-up" contribution for employees who are between the ages of 60 through 63. A regular 401(k) allows these same employees to elect deferrals of up to $24,500.^[2] The employer-side limits apply as well. There is a maximum employer match or non-elective contribution that will qualify as a SIMPLE Plan (which is referred to as the 3% match or the 2% non-elective contribution), whereas it should be noted that no discretionary profit sharing comes into play here like it does with a regular 401(k). Because the SIMPLE 401(k) is considered a qualified retirement plan, there are certain limitations applicable to such plans regarding compensation, including the 401(a)(17) compensation limit applicable to employer matching contributions. These types of limitations do not exist when using a SIMPLE IRA plan match.

That deferral ceiling is the single biggest reason you would reconsider a plan. The 2026 limit varies significantly across the three plans which are considered by an actual small employer:

Because of the presence of 401(k) in the name of the plan, owners have assumed that this plan will carry with it a higher deferral limit for 401(k). It doesn't. The SIMPLE 401(k) is locked to the SIMPLE elective-deferral limit defined under Internal Revenue Code Section 401(k)(11), which created it and ties it to the SIMPLE contribution rules.^[3] Thus, an owner who wishes to shelter $24,500 may only defer up to $17,000 for 2026 plus any additional catch-up contributions based on age. If increasing the deferral limit is your goal then you should consider using a safe harbor 401(k) plan which has a much greater ceiling than do SIMPLE plans. Check the deferral limits against the SIMPLE IRA contribution limits for 2026 before you assume that having "401(k)" included within your plan's name gives you more available space to defer funds.

SIMPLE 401(k) vs SIMPLE IRA vs safe harbor 401(k)

In order to establish where a SIMPLE 401(k) belongs, you need to compare it to the other two options that it competes with. The cost and ease of administration are where the SIMPLE IRA will win out. However, the amount you may be able to contribute toward an employee's retirement account under a safe harbor 401(k) will exceed what may be contributed under a SIMPLE Plan. Therefore, we would consider a SIMPLE 401(k) a compromise that incorporates elements of both plans' disadvantages into one offering. There are five characteristics that determine this decision:

The issue lies within the SIMPLE 401(k) column. It is essentially the same as the SIMPLE IRA with regards to deferral limits and vesting, and the same as the safe harbor on paperwork and loan options, but does have an additional requirement of filing the Form 5500, which the SIMPLE IRA never files. In addition, it has a cap on savings that is $7,500 lower than the safe harbor plan. For that ordinary small business considering a SIMPLE IRA versus a 401(k) plan, the SIMPLE 401(k) would rarely come out ahead.

Why do so few employers use a SIMPLE 401(k)?

A SIMPLE 401(k) survives mostly on paper, as the marketplace almost never selects this option. A qualified plan (or "QP") has an on-going administrative burden, including an annual Form 5500 return from the QP along with a recordkeeper/third party administrator to manage the trust, yet contributions are capped at the low SIMPLE limit.^[4] A SIMPLE IRA provides the same $17,000 maximum contribution amount with no Form 5500 and requires only a two page adoption form. A Safe Harbor 401(k) will provide similar administrative costs. However, participants can defer the full $24,500 and add profit-sharing on top. In addition, since a Qualified Plan is covered under ERISA, employers must distribute a Summary Plan Description ("SPD"), obtain an ERISA fidelity bond and correct any operational error(s) through the IRS correction process, none of which apply to Simple IRAs. The safe harbor plan was introduced shortly after Congress passed legislation creating the SIMPLE 401(k) in 1996 providing similar testing relief while allowing for much larger deferred amounts, therefore most record-keeping companies do not even keep copies of the SIMPLE 401(k) document today. Both SIMPLE plans are laid side-by-side by IRS Publication 560, and the IRA version fits virtually every small business that would have otherwise considered the 401(k) version.^[5]

The Bottom Line

Choose a SIMPLE 401(k) only if you specifically need participant loan provisions or an ERISA trust, and can live with the lower SIMPLE deferral limit. A SIMPLE IRA is likely your best choice when you do not need either of those features, since it skips the Form 5500 entirely. A Safe Harbor 401(k) is likely your best option when you want the 2026 deferral limit raised to the $24,500 level. Choose that plan which has at least one benefit you will use: loans, no Form 5500, or the higher cap.

This guide is educational and summarizes IRS rules for SIMPLE 401(k) plans. It is not investment, legal, or tax advice. Your plan documents and current IRS limits control. Talk to your tax advisor about your business's circumstances.