Most business owners do not need the retirement plan that is “best” in general. They need the plan that best fits how their business is structured today. Yet many owners choose a plan once — often when the business is smaller and never revisit it as income rises, employees are added, cash flow changes, or tax-planning goals become more aggressive. That can quietly limit how much they can save and how effectively those contributions reduce current taxable income.
The two plans business owners compare most often are the SEP IRA and the 401(k), including the Solo 401(k) for an owner with no eligible common-law employees other than a spouse. People sometimes treat them as interchangeable ways to make a large deductible retirement contribution. They are not. The contribution mechanics, employee obligations, administrative requirements, and planning opportunities are different enough that the right choice can change as the business changes.
What a SEP IRA Actually Gives You
A SEP IRA is built for simplicity. Contributions are employer contributions only; there is no employee salary-deferral feature. For 2026, an employee can generally contribute up to 25% of compensation, subject to the $72,000 annual limit. Self-employed owners use a special calculation based on net earnings from self-employment, so the practical percentage is not simply 25% of Schedule C profit. A major advantage is timing: you can generally make the employer contribution as late as the business tax-return due date, including extensions, giving owners flexibility when final income and cash flow aren’t known until after year-end.
The tradeoff is that SEP contributions generally must use the same contribution percentage for all eligible employees. That is easy to overlook. A 20% owner contribution may also mean a 20% employer contribution for every eligible employee. For a solo owner, that may not matter at all; for a growing company, it can make a SEP far more expensive than it first appears. The SEP also does not provide participant loans or employee Roth salary deferrals.
What a 401(k) Actually Gives You
A 401(k) works differently because it can combine employee salary deferrals with employer contributions. For 2026, the regular employee elective-deferral limit is $24,500. If the plan permits catch-up contributions, participants age 50 or older can generally defer an additional $8,000, while participants ages 60 through 63 can qualify for a higher $11,250 catch-up. Employer contributions can then be added, subject to the plan rules and the overall 2026 defined-contribution limit of $72,000 before catch-up contributions. That means the total can reach $80,000 for many participants age 50 or older, or $83,250 for participants ages 60 through 63. A 401(k) may also permit Roth deferrals and participant loans. The tradeoff is greater administration, plan-document requirements, and potentially testing and additional employer costs once employees are involved.
The Question That Actually Matters
The real decision is not which plan is more popular. It is which plan creates the best combination of contribution capacity, employee cost, flexibility, and administration for your actual business. The right answer depends on more than income alone: entity type, W-2 wages or self-employment income, age, number of employees, compensation levels, desired owner contribution, cash flow, and whether Roth or loan features matter can all change the result.
For example, a solo owner with sufficient earned income may reach a desired contribution with a Solo 401(k) at a lower income level because the employee deferral is layered on top of the employer contribution. By contrast, an owner with several employees may care less about the theoretical maximum and more about what the plan requires the company to contribute for staff. In that situation, model the comparison before selecting the planis selected —not after the contribution decision has already been made.
It’s Not About Having Every Retirement Account. It’s About Having the Right One
More accounts do not automatically create a better retirement strategy. What matters is coordinating the accounts that fit your business, your household, and your tax plan — and then funding them consistently. Traditional and Roth IRAs may still have a role alongside an employer plan, but their eligibility and deductibility rules are separate. Choose the business retirement plan first for what it is designed to accomplish, not simply because it has the highest advertised contribution limit.
Where Do You Stand Right Now?
- Do you know whether your business currently qualifies for a Solo 401(k), a SEP IRA, or both?
- Have you modeled the actual contribution available from your current compensation or self-employment income — not just looked at the maximum annual limit?
- If you have employees, have you calculated what an owner contribution would require the business to contribute for them under each plan?
- Have you reviewed whether Roth contributions, catch-up contributions, participant loans, or future hiring plans change which plan fits best?
If you answered “no” or “not sure” to more than one of these, the plan deserves a fresh review before year-end. Retirement planning is much more useful when you model the contribution strategy while you still have time to decide, rather than after the tax return is already being prepared.
This is exactly the kind of decision our team at BASC helps business owners work through using the actual business structure, compensation, employee census, cash flow, and tax goals rather than a generic contribution-limit chart. If you want a second set of eyes on whether your current retirement plan still fits where your business is today, call us at 480-355-1398, email info@bascexpertise.com, or schedule a strategy session at www.bascexpertise.com. For a broader walkthrough of 401(k) and Solo 401(k) plans, SEP IRAs, traditional and Roth IRA strategies, spousal planning, contribution deadlines, and related retirement-planning opportunities, request your complimentary copy of BASC Blueprint 05: Retirement & Wealth-Building Tax Strategies.