Should I Choose a Defined Benefit Plan or 401(k) for My Small Business?

Choosing between a defined benefit plan and a 401(k) is one of the most impactful retirement planning decisions a small business owner can make. Each plan type offers distinct advantages, and the right choice depends on your income level, age, number of employees, and how much you want to shelter from taxes. In many cases, the optimal answer is both -- but understanding each plan individually is the starting point.

How a 401(k) Works for Business Owners

A 401(k) plan under IRC Section 401(k) allows participants to make employee deferrals from their compensation, and the employer can make matching or profit-sharing contributions. The total annual contribution is capped at $70,000 for 2026 under IRC Section 415(c), plus catch-up contributions for those age 50 or older. The employee deferral portion is $23,500, with the remainder coming from employer contributions up to 25% of compensation.

The 401(k) is straightforward to administer, relatively low-cost, and provides predictable annual contribution limits. Contributions are discretionary -- you can contribute the maximum in a good year and reduce or skip contributions in a lean year without penalty or funding obligations. Investment risk falls on the participant, and account balances fluctuate with market performance.

How a Defined Benefit Plan Works

A defined benefit plan under IRC Section 414(j) promises a specified monthly benefit at retirement age, and the employer must contribute enough each year to fund that promise. An enrolled actuary calculates the required annual contribution based on the participant's age, salary, target benefit, assumed investment return, and the plan's funded status. Because the plan guarantees a retirement benefit, the employer bears the investment risk.

The maximum annual benefit at retirement is limited by IRC Section 415(b)(1)(A) to $280,000 per year (as adjusted for 2026). The annual contribution needed to fund this benefit depends heavily on the participant's age at plan inception -- older participants need larger contributions because they have fewer years to accumulate and grow the funds. This age-based dynamic is what makes defined benefit plans especially powerful for business owners over 40.

Contribution Limit Comparison

This is where the difference becomes dramatic. A 45-year-old business owner can typically contribute $100,000 to $150,000 annually to a defined benefit plan. A 55-year-old might contribute $200,000 to $250,000. A 60-year-old can potentially contribute $300,000 or more. Compare this to the 401(k) maximum of $70,000 to $77,500 -- the defined benefit plan offers contribution capacity that is two to four times larger.

Every dollar contributed to either plan is tax-deductible to the business and tax-deferred for the participant. For a business owner in the 37% federal bracket, the difference between contributing $70,000 (401(k) only) and $250,000 (defined benefit plan) represents approximately $66,600 in additional federal tax savings -- in a single year.

Cost and Complexity

A 401(k) plan can be established through most financial institutions with minimal setup cost and annual administration fees of $500 to $2,000. A defined benefit plan requires an enrolled actuary to design the plan, calculate annual contributions, and ensure compliance with IRS nondiscrimination rules. Annual administration costs typically range from $2,000 to $5,000 -- but easily justified when the tax savings exceed the administration expense by a factor of 20 or more.

Employee Considerations

Both plan types must satisfy coverage and nondiscrimination requirements under IRC Sections 410(b) and 401(a)(4). If you have employees, you must generally include them in the plan. For a 401(k), employer matching or profit-sharing contributions for employees are an additional cost. For a defined benefit plan, the actuary calculates the required contribution for each covered employee based on their age and compensation -- younger, lower-paid employees typically require smaller contributions, which keeps the cost manageable.

Solo business owners with no employees (other than a spouse) have the most flexibility because there are no nondiscrimination concerns.

Funding Commitment

One significant difference is the funding obligation. A 401(k) allows discretionary contributions -- you can contribute nothing in a bad year. A defined benefit plan requires minimum annual contributions determined by the actuary. If your business income is volatile, the mandatory contribution requirement can create cash flow pressure in down years, though most plans are designed with some contribution flexibility built into the actuarial calculations.

The Combined Approach

Many business owners implement both plans simultaneously -- a 401(k) profit-sharing plan plus a cash balance defined benefit plan. This combination maximizes the total deductible contribution by stacking the 401(k) limit on top of the defined benefit plan contribution. If you want to shelter more than $70,000 per year, a defined benefit plan -- alone or in combination with a 401(k) -- is the way to get there. A retirement plan specialist can model both scenarios using your actual income and employee data to show the exact tax impact of each option.

This article is for informational purposes only and does not constitute legal or tax advice. Consult a qualified tax professional regarding your specific circumstances. AE Tax Advisors, 935 Lake Elmo Dr, Suite B, Billings, MT 59105. Phone: (631) 614-5762.