SIMPLE 401(k)
A SIMPLE 401(k) is a simplified defined contribution retirement plan available to employers with 100 or fewer employees under IRC Section 401(k)(11). It combines the employee deferral feature of a standard 401(k) with mandatory employer contributions similar to those required under a SIMPLE IRA, while eliminating the need for complex nondiscrimination testing. The trade-off is that the plan is subject to employer contribution requirements and lower deferral limits than a full-feature 401(k).
Congress created the SIMPLE 401(k) in 1996 alongside the SIMPLE IRA to give small employers a straightforward qualified plan option that exempts them from the ADP (Actual Deferral Percentage) and ACP (Actual Contribution Percentage) nondiscrimination tests that govern traditional 401(k) plans. These tests are designed to ensure that high-paid employees do not receive disproportionately larger tax benefits than lower-paid participants, but compliance is administratively burdensome for small businesses with limited HR resources.
The SIMPLE 401(k) exemption from testing comes with mandatory employer contribution obligations. The employer must choose one of two contribution formulas each plan year: (1) a dollar-for-dollar match of employee deferrals up to 3% of each employee's compensation, or (2) a non-elective contribution of 2% of compensation for all eligible employees, whether or not they defer. These contributions vest immediately — 100% vesting is required upon contribution, with no cliff or graded schedule. The employer cannot impose any other contribution formulas or matching structures on a SIMPLE 401(k) in the same year.
Employee elective deferral limits for a SIMPLE 401(k) in 2025 are $16,500, compared to $23,500 for a traditional 401(k). The catch-up contribution for participants age 50 and older is $3,500 (versus $7,500 in a traditional 401(k), or $11,250 for ages 60-63 under SECURE Act 2.0). These lower limits are a significant disadvantage for high-income employees who want to maximize tax-deferred savings, and they partly explain why SIMPLE 401(k) plans are less commonly adopted than SIMPLE IRAs or safe harbor 401(k) plans.
Because the SIMPLE 401(k) is a qualified plan under IRC Section 401(a), participants have access to 401(k) loan provisions, which SIMPLE IRAs do not offer. This feature can be attractive to employees who want a retirement plan that also functions as an accessible emergency savings backstop, though financial advisors generally caution against using retirement plan loans due to the risk of the loan being treated as a taxable distribution if the employee leaves the employer with an outstanding balance.
Employers who exceed 100 employees in a subsequent year must transition to a different plan type by the end of a two-year grace period. The SIMPLE 401(k) is not as widely adopted as the SIMPLE IRA primarily because it requires a formal plan document and annual Form 5500 filing, while SIMPLE IRAs are established using standardized IRS forms (Forms 5304-SIMPLE or 5305-SIMPLE) with minimal administrative burden. For many small employers, the SIMPLE IRA remains the simpler and lower-cost alternative despite offering fewer participant features.