The Small Business 401(k) Guide

Choosing the Right Retirement Plan for Your Growing Business

Selecting a retirement plan is a significant milestone for any growing business with full-time employees. The right choice requires balancing your team's size, your desired contribution flexibility, and the level of administrative complexity you're prepared to manage. Among the most common solutions are the Safe Harbor 401(k), the SEP IRA, and the SIMPLE IRA, each offering distinct advantages depending on your specific business goals. All figures below reflect 2026 IRS limits and are subject to future cost-of-living adjustments and legislative change.

Safe Harbor 401(k)

The Safe Harbor 401(k) is often considered a strong fit for high-earning owners who want to maximize their personal retirement savings, with an employee deferral limit of up to $24,500 in 2026. It can also be an attractive benefit for businesses looking to attract and retain talent. One of its primary features is that it automatically satisfies the IRS ADP/ACP nondiscrimination tests, provided the employer commits to one of three prescribed contribution formulas: (1) a basic match of 100% on the first 3% of compensation deferred plus 50% on the next 2% (totaling up to 4% for an employee deferring at least 5%); (2) an enhanced match that is at least as generous as the basic formula at each tier (commonly 100% on the first 4%); or (3) a non-elective contribution of at least 3% of compensation to all eligible employees regardless of whether they defer. Safe harbor contributions must be 100% immediately vested.

Unlike SEP and SIMPLE IRAs, a 401(k) can permit participant loans (up to the lesser of $50,000 or 50% of the vested account balance) if the plan document allows. However, the plan does require annual Form 5500 filing and generally carries more operational overhead than IRA-based plans.

For participants ages 50–59 and 64+, an additional catch-up contribution of $8,000 is available in 2026. Participants ages 60–63 may make an enhanced catch-up of up to $11,250 in lieu of the standard catch-up, if the plan permits. When combined with the 2026 defined-contribution annual additions limit of $72,000, the total possible annual contribution for a 60–63-year-old participant could reach $83,250.

Beginning January 1, 2026, under SECURE 2.0 final regulations, catch-up contributions for participants whose prior-year FICA wages (Box 3 of the W-2) from the sponsoring employer exceeded $150,000 must be made as Roth (after-tax) contributions. This rule applies to 401(k), 403(b), and governmental 457(b) plans, not to SIMPLE IRAs. If a plan does not offer a Roth feature, affected participants may be unable to make catch-up contributions at all.

SEP IRA

For businesses with strong profits that prefer minimal administrative overhead, the SEP IRA is an effective and flexible alternative. It offers straightforward setup and no annual Form 5500 filing in most cases. Unlike a 401(k), a SEP IRA is funded entirely by employer contributions, which must be applied as a uniform percentage of compensation across all eligible employees. Contributions are 100% immediately vested.

For 2026, the employer contribution limit is the lesser of 25% of eligible compensation (20% of net earnings from self-employment for a sole proprietor, after certain adjustments) or $72,000 per employee. SEP IRAs do not permit employee salary deferrals or catch-up contributions. A key advantage for busy owners is deadline flexibility: a SEP IRA can generally be established and funded as late as the business's tax filing deadline, including extensions. SEPs can be a good fit for self-employed individuals and small firms, though owners planning to add employees should model the cost, because the same percentage applied to the owner must also be applied to each eligible employee.

SIMPLE IRA

Small teams with 100 or fewer employees often find the SIMPLE IRA to be a lower-cost starter plan that provides 401(k)-style employee deferrals with less overhead and no nondiscrimination testing. For 2026, employee deferrals are limited to $17,000 under the standard rules. SECURE 2.0 allows certain employers to adopt "enhanced" limits, increasing the deferral cap to $18,100 for eligible plans.

The enhanced limits apply automatically for employers with 25 or fewer eligible employees who earned at least $5,000 in the prior year. Employers with 26–100 employees may elect the higher $18,100 limit only if they provide an enhanced employer contribution—either a 4% match (up from the standard 3%) or a 3% non-elective contribution (up from the standard 2%).

Catch-up contributions are available for older participants. In 2026, individuals ages 50 and older may contribute an additional $4,000 under the standard rules, or $3,850 in a plan using the enhanced limits. Participants ages 60–63 may instead use the SECURE 2.0 "super catch-up," allowing an additional $5,250, regardless of whether the plan uses standard or enhanced limits.

Employer contributions must follow one of the IRS-prescribed formulas—generally a 3% dollar-for-dollar match or a 2% non-elective contribution—and are required for all eligible staff. Like the SEP IRA, the SIMPLE IRA does not require an annual Form 5500 filing. Existing businesses generally must establish a SIMPLE IRA by October 1 of the plan year; new businesses formed later in the year can typically establish one as soon as administratively feasible.

Incentives to Get Started

To further support small businesses, the SECURE Act 2.0 provides several tax credits for starting a new plan:

• Startup Credit: Employers with 50 or fewer employees may claim a credit equal to 100% of qualifying startup and administrative costs, up to $5,000 per year for three years. Employers with 51–100 employees may claim 50% of qualifying costs, subject to the same $5,000 annual cap.

  
  

• Employer Contribution Credit: For employers with 50 or fewer employees, a credit of up to $1,000 per employee earning $100,000 or less applies to employer contributions. The credit is 100% in years 1 and 2, 75% in year 3, 50% in year 4, and 25% in year 5, phasing out entirely thereafter. The credit is reduced for employers with 51–100 employees.

  
  

• Auto-Enrollment Credit: A flat $500 annual credit for three years is available for adding an eligible automatic enrollment feature to a new or existing plan.

  
  

All contribution limits, thresholds, and credit amounts referenced here reflect current federal tax law as of 2026 and are subject to change with future legislation or IRS guidance.

Choosing What Fits Your Business

Selecting the right retirement strategy is a significant step in your business's long-term financial health. Because tax laws and retirement plan regulations are complex and frequently updated, we encourage you to consult with a qualified tax professional, ERISA attorney, or financial advisor before establishing or amending a plan.

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This material is for general educational purposes only and is not intended as, and should not be relied upon for, tax, legal, ERISA, or individualized investment advice. Contribution limits, thresholds, credit amounts, and plan rules are based on federal tax law in effect as of 2026 and may change. Individual circumstances vary; please consult qualified professionals regarding your specific situation. Longevity Wealth Advisory is a state-registered investment adviser; registration does not imply a certain level of skill or training.