Buford was a factory town before it was anything else. The Bona Allen tannery ran here for more than a century, at its peak turning out thousands of pairs of shoes a day and enough saddles and harness that Hollywood cowboys sent their horses to Buford to be fitted. When the leather operation finally shut down in the eighties, what was left was a town full of people who knew how to make things and work for themselves.That is still the character of the place. Buford straddles the Gwinnett and Hall county line, sits on Lake Lanier, and has a business base heavy on owner-operators: contractors, marine and dock services, landscaping outfits, specialty trades, small distribution operations, and a long list of one-truck-and-a-crew companies that grew into real businesses without ever adding an HR department.For those owners, the retirement plan question almost always arrives in the same form. The CPA says you should put money away. Somebody mentions a SEP-IRA. Somebody else mentions a solo 401(k). Nobody explains the difference in a way that connects to your actual business, so it sits.
The Question That Actually Decides It
Before comparing features, one question settles most of this: does your business have employees?A solo 401(k) is built for owner-only businesses. You and a spouse who works in the business can participate. Once you have full-time employees who meet the eligibility rules, a solo 401(k) is no longer the right vehicle, and the business is looking at a regular 401(k) plan instead.A SEP-IRA can cover employees, but it covers them on the employer’s terms in a specific way: contributions are made as a uniform percentage of compensation. If you contribute a given percentage for yourself, eligible employees generally get the same percentage. There is no employee deferral component and no way to contribute generously for yourself and modestly for the crew.For a Buford contractor with six employees, that single sentence often ends the conversation, because the cost of covering the crew at the percentage the owner wants for themselves is far larger than the tax benefit. For a genuinely owner-only operation, it never comes up at all.
How the Two Plans Fund
A SEP-IRA is funded entirely by the business. There is no salary deferral. The business contributes a percentage of compensation, subject to a ceiling, and that is the whole mechanism. Simple, and simple has real value.A solo 401(k) has two funding sources. You contribute as an employee through salary deferral, and the business contributes on top as the employer. Two doors into the same account.That structural difference drives the outcome most owners care about. Because the solo 401(k) allows a deferral before the percentage-based employer contribution is calculated, it typically lets an owner reach a given contribution level on less income than a SEP-IRA requires. At high profit both plans can reach the same ceiling. Below that, the solo 401(k) usually wins on room, and the margin can be substantial for a business with modest profit relative to the owner’s savings goal.The solo 401(k) also offers things the SEP-IRA does not: a Roth option on the deferral portion, catch-up contributions once you become eligible for them, and in many plan documents the ability to borrow from the plan. Whether any of those matter depends on your situation, and the Roth question in particular should be answered against your tax picture rather than by default.
Where the SEP-IRA Still Wins
Simplicity and timing.A SEP-IRA can generally be established and funded after the tax year has already ended, up to the business return deadline including extensions. That is a real advantage for an owner who does not know what the year produced until the CPA finishes the return, which describes a lot of construction and seasonal businesses around the lake. Set it up in the spring, fund it based on what actually happened, done.Solo 401(k) timing is less forgiving. The plan generally has to exist and the deferral election has to be handled within the tax year itself, with a narrow exception available to newly established plans in their first year for certain owners. Miss the timing and the deferral half of the plan is simply unavailable for that year, which removes most of the reason to have chosen it.The SEP-IRA also carries almost no administration. A solo 401(k) is a qualified plan with a plan document, and once plan assets pass a threshold the business picks up an annual filing requirement. Not difficult, but it is a real obligation and the penalties for ignoring it are not trivial.
The Piece Owners Get Backwards
Both of these are containers. Neither is a strategy.The most common pattern is an owner who set up a SEP-IRA years ago because it was easy, has been funding it to the ceiling ever since, and assumes the retirement question is handled. If the business profit has grown well past what these plans can absorb, that ceiling is now the constraint, and the money above it is simply landing on the tax return every year with no plan attached.That is the point where the conversation moves to profit sharing designs and, for consistently high profit, to a defined benefit structure layered on top. The cash balance plan post covers what that looks like and, more importantly, who it is wrong for.There is also an entity interaction that catches S-Corp owners. The employer contribution is calculated off W-2 compensation, so a salary set purely to minimize payroll tax can quietly cap what the business is allowed to contribute for you. That is one of several reasons the salary number deserves more thought than it usually gets, which the S-Corp salary post works through.
How to Actually Decide
The order that works is boring and reliable. Start with whether you have eligible employees, because that eliminates one option outright in most cases. Then look at profit and how much of it you want to put away, which tells you whether the solo 401(k)’s extra room matters or whether both plans reach your number anyway. Then look at how predictable the year is, because an owner who cannot forecast profit until spring may value the SEP-IRA’s timing more than the extra contribution room. Then confirm the choice against your entity structure and compensation, since those set the inputs.None of that requires a specialist. It requires somebody looking at all four at once instead of answering whichever question landed in front of them.Matt Losanno works with business owners on exactly that coordination. As a financial advisor serving Buford and the Gainesville, GA area, his role is to connect the retirement plan choice to the entity structure, the compensation strategy, and the longer plan for building wealth outside the business, in coordination with your CPA rather than around them.
See Where Your Tax Strategy Stands
Free. Five minutes. Built around your actual situation, not generic assumptions.Get the Free AssessmentOr if you want to go deeper, you can schedule a Tax Strategy Review directly.This content is for educational and informational purposes only. It does not constitute tax, legal, or investment advice. Contribution limits, eligibility rules, establishment and funding deadlines, filing thresholds, and catch-up provisions for SEP-IRAs and solo 401(k) plans are set by federal law, change periodically, and are not summarized in full here. Consult your CPA and financial advisor before establishing or funding any retirement plan.
