Solo 401k vs Pension Structures
By Michael Freeman | Acacia
One of the more common questions I see from self-employed professionals and small business owners is whether a solo 401 (k) or a defined-benefit pension plan is the better vehicle. The answer depends heavily on income level, age, time horizon, and what the person is actually trying to accomplish with retirement capital.
Both structures carry significant tax advantages. Both allow the account holder to accumulate capital in a tax-advantaged environment. But they operate very differently, and confusing them or defaulting to one without understanding the other is a planning mistake worth avoiding.
The Solo 401k
A solo 401k (also called an individual 401k or owner-only 401k) is designed for self-employed individuals or business owners with no full-time employees other than a spouse. It mirrors the structure of a corporate 401k in most respects, allowing both employee contributions and employer profit-sharing contributions.
For 2024, the combined employee and employer contribution limit is $69,000, with an additional $7,500 catch-up contribution available for those 50 and older. For someone with relatively high self-employment income, this ceiling allows for meaningful annual contributions without the complexity of an actuarial calculation.
The solo 401 (k) also permits Roth designation for the employee contribution portion, which is worth noting for anyone whose income projections suggest that tax-free growth is more valuable than an upfront deduction. Additionally, solo 401k plans can be structured to allow participant loans, which defined benefit plans typically do not.
On the self-directed side, a solo 401k with the right plan document can hold the same alternative assets discussed in the context of IRAs: real estate, private notes, private equity, and similar instruments. This flexibility is one of the more compelling aspects of the structure.
Defined Benefit Pension Plans
A defined benefit plan operates on a fundamentally different premises. Rather than defining what goes in (contributions), it defines what comes out (a promised benefit at retirement). The annual contribution is then calculated by an actuary to fund that promised benefit, working backward from the target payout.
For high-income individuals, particularly those who are older and starting retirement savings later, a defined benefit plan can permit substantially larger annual deductions than a 401 (k). It is not unusual for a well-structured defined benefit plan to allow contributions of $150,000 to $300,000 or more per year depending on age and income. For someone in a high tax bracket, those deductions carry real weight.
The tradeoff is complexity and cost. Defined benefit plans require annual actuarial certification, are subject to IRS minimum funding standards, and carry penalties for underfunding. They are not flexible in the way a 401k is; once the promised benefit is established, meeting the funding requirement is an obligation, not an election.
Combining Both
One approach worth understanding is using both structures simultaneously. A solo 401k and a defined benefit plan can coexist for a self-employed individual, and the contribution limits are not fully additive but do stack in a meaningful way. When combined, total annual deductible contributions can be substantially higher than either structure would permit on its own.
This combination is particularly effective for high-earning professionals in their 50s who are looking to reduce current tax exposure while building a substantial retirement base over a 10- to 15-year window. It is not a simple setup, and it requires coordinated plan documents and actuarial support, but it is a legitimate and well-used strategy.
Acacia works with clients navigating exactly this kind of multi-plan structuring. If you are evaluating which vehicle fits your income profile and timeline, that conversation is worth having directly. Additional structuring commentary is available at MichaelIoane.com.
The information in this article reflects general structural principles and practical observations from consulting experience and is provided for educational purposes only. It should not be interpreted as individualized legal or tax advice.