Solo 401(k) vs SEP-IRA for Self-Employed Real Estate Investors

Please note: AllApprovedHere.com and Barrett Financial Group, LLC are a licensed mortgage broker (NMLS #181106) — not a tax advisor, CPA, or law firm. This article is general education, not tax, legal, or investment advice. Tax rules change and outcomes depend on your specific situation. Consult a qualified CPA or tax professional before acting on any strategy described here.

If you earn self-employment income from real estate — flipping houses, wholesaling, earning commissions, running a development business, or doing 1099 contract work — you have access to retirement accounts that most W-2 employees can only dream about. The two workhorses are the Solo 401(k) and the SEP-IRA. Both let you deduct contributions against self-employment income, both grow tax-deferred, and both can be opened without a big company plan behind you. But they are built very differently, and the differences change which one fits your situation.

This guide walks through the mechanics of each, compares them side by side, and covers the special question real estate investors always ask: can the account itself own property? (Short answer: sometimes, with serious caveats.) This is education, not advice — contribution math and plan selection depend on your entity type, income, and goals, so run your specific numbers with a CPA or qualified plan professional before you open anything.

A SEP-IRA (Simplified Employee Pension) is the minimalist option. There is only one type of contribution: an employer contribution, calculated as a percentage of your compensation. If you operate as a sole proprietor or single-member LLC, the math works out to roughly 20% of your net self-employment earnings after the self-employment-tax adjustment. If you pay yourself W-2 wages through an S-corp, it is generally up to 25% of those wages. Either way, the total is capped at current IRS limits, which adjust annually.

The appeal is simplicity. You can open a SEP at almost any brokerage with a short adoption form, there is no annual plan filing, and — uniquely — you can open and fund it after the year ends, all the way up to your tax-filing deadline including extensions. That makes it a popular catch-up move for investors who had a big flip or commission year and only realize in March that they want a deduction.

The tradeoffs: contributions are employer-only, so a moderate-income year supports a much smaller contribution than a Solo 401(k) would allow. And if you have eligible employees, you must contribute the same percentage for them that you contribute for yourself — which can get expensive fast for a growing contracting or development business.

A Solo 401(k) (also called an individual or one-participant 401(k)) is a full 401(k) plan scaled down to a business with no employees other than an owner and, potentially, a spouse. Its power comes from having two contribution buckets:

1. Employee salary deferral. You can defer compensation up to the current IRS deferral limit — and unlike the SEP's percentage math, this bucket can be up to 100% of your compensation until the limit is reached. Those age 50 and up get an additional catch-up amount.
2. Employer profit-sharing. On top of your deferral, the business can contribute using essentially the same percentage formula a SEP uses.

Stacking the two buckets is why the Solo 401(k) usually allows larger total contributions at low and moderate income levels — the same combined ceiling as a SEP only converges at high incomes.

Three features matter beyond raw capacity. Most Solo 401(k) plans offer a Roth option for the employee deferral, letting you pay tax now in exchange for tax-free qualified growth. Many plans permit loans — generally up to half your vested balance, capped at current IRS limits — which some investors use as short-term liquidity for earnest money or rehab overruns (repayment terms are strict, so treat this carefully). And a working spouse who earns compensation from the business can participate too, roughly doubling what a household can shelter.

The cost is modest administration: you need a formal plan document, and once plan assets pass the current IRS reporting threshold you must file a short annual return (Form 5500-EZ). Miss that filing and penalties are ugly — a good reason to involve a professional plan provider.

Here is the mechanic that trips up more real estate investors than any other: both accounts require compensation — earned income — not passive income.

Rental income from buy-and-hold properties is generally not self-employment compensation, so it cannot support Solo 401(k) or SEP contributions by itself. What does count, generally speaking:

• Profits from flipping or wholesaling (dealer activity is ordinary income subject to self-employment tax — painful in most contexts, but it is exactly what makes these accounts available)
• Commissions earned as a licensed agent or broker
• 1099 contractor income — construction, project management, consulting, property management fees
• W-2 wages you pay yourself through your own S-corp

So a pure landlord with no active business income typically cannot contribute, while a flipper, agent, or contractor can. Investors who do both sometimes find that the active side of their business funds the retirement plan while the passive side builds equity — but how your entities are structured drives all of this, and it is squarely a conversation for your CPA.

Hypothetical for illustration only — not a projection of your results. Suppose a self-employed flipper nets $100,000 of self-employment earnings in a year, files as a sole proprietor, and is under age 50.

• With a SEP-IRA, the contribution is limited to the employer percentage — roughly 20% of adjusted net self-employment earnings, so somewhere in the neighborhood of $18,000–$19,000 depending on the exact self-employment-tax math.
• With a Solo 401(k), that same employer share is available plus the full employee deferral up to the current IRS limit. The combined total can land well above the SEP figure — roughly double, and sometimes more, at this income level.

At very high incomes the two converge, because both share the same overall annual cap under current IRS limits. But in the income range where most solo investors and contractors actually live, the Solo 401(k)'s stacked structure usually supports a meaningfully larger deductible contribution. Whether a larger contribution is actually the right move — versus keeping capital liquid for the next deal — is a planning question, not a math question, and worth modeling both ways with your tax professional.

Both account types can be set up as self-directed, meaning the account itself — not you personally — can own alternative assets, including rental real estate, private notes, and syndication interests. For investors who want their retirement dollars in an asset class they understand, this is genuinely interesting. It is also where people get hurt, so know the guardrails:

• Prohibited transactions. You, your spouse, your lineal family, and entities you control are disqualified persons. The account cannot buy property from you, sell to you, rent to your kid, or let you stay in the property — and you generally cannot do your own repair work on an account-owned asset (sweat equity is a contribution problem). The consequences are severe either way: a single prohibited transaction in a self-directed IRA can disqualify the entire account, potentially making the whole balance taxable at once, while in a Solo 401(k) it generally triggers excise taxes and mandatory correction instead — still an expensive mistake.
• Leverage triggers tax. An IRA that buys property with a mortgage generally owes tax on the debt-financed share of income and gains (UBIT/UDFI). Solo 401(k)s enjoy a notable exemption for typical real estate acquisition debt under current law — one reason self-directed investors often prefer the 401(k) wrapper — but verify how the rules apply to your structure.
• Non-recourse financing only. Loans inside a retirement account cannot carry your personal guarantee, which narrows lender options and typically means lower leverage.
• No depreciation benefit to you. Property inside a tax-deferred account doesn't generate deductions on your personal return — you give up depreciation, cost segregation, and 1031 tools that make directly-owned real estate tax-efficient.

This is one of the most technical corners of retirement law. Do not attempt a self-directed real estate purchase without a CPA or ERISA attorney who works in this space regularly.

Retirement contributions and mortgage qualification touch in ways worth understanding before you commit to a big contribution.

Large deductible contributions reduce the taxable income shown on your returns. For conventional full-documentation loans, that lower net income can shrink what a lender calculates as your qualifying income — a real tension for self-employed borrowers who both want deductions and want to finance the next property.

This is one reason many self-employed investors use DSCR loans for rental acquisitions: qualification is based primarily on the property's rent covering its payment, not on personal tax returns, so an aggressive Solo 401(k) contribution doesn't work against the file the way it can on a conventional application. All financing remains subject to qualification and underwriting approval, but the documentation path matters, and it is worth discussing with your loan officer and your CPA together before year-end, so the tax plan and the acquisition plan don't collide.

One more note: if a self-directed account owns the property, standard investor loans don't apply — the account needs non-recourse financing, which is a specialized product. Personally-owned rentals financed with DSCR or conventional investor loans, alongside a retirement account funded by your active income, is the simpler and more common structure.