Solo 401(k) vs Self-Directed IRA for Private Lending
For self-employed investors a solo 401(k) can beat an SDIRA on contribution limits, cost and leveraged real estate income. When it does, and when it does not.
Who can even have a solo 401(k)
Two conditions, and the first one fails more often than people expect.
Genuine self-employment income. A solo 401(k) is an employer plan and it needs an employer. That means net earnings from self-employment as a sole proprietor or partner, or W-2 wages from your own S corporation. Consulting income, a professional practice, a brokerage, a construction business, a side business run seriously: all fine.
What is generally not self-employment income is the part that catches real estate investors. Rents from a portfolio of rental properties are ordinarily passive income, not self-employment income. Interest, dividends and capital gains are not either. An investor with twelve doors, no job and no operating business frequently discovers that the vehicle everyone recommended is not available to them. Confirm your own facts with your CPA before you spend a dollar on a plan document.
No full-time employees other than you and your spouse. The plan document can exclude certain categories, and the treatment of long-term part-time employees has been revised in recent years, so this is an area to confirm against current rules rather than against an article. The test is also ongoing. Hire a qualifying full-time employee and the plan's status has to be revisited, which is a live issue for a business that grows.
Side-by-side comparison
| Solo 401(k) | Self-directed IRA | |
|---|---|---|
| Eligibility | Self-employment income, no full-time employees besides spouse | Anyone with earned income or an existing balance to roll over |
| Annual contribution capacity | Employee deferral plus employer contribution, so a multiple of the IRA limit | The single IRA limit |
| Specific limits | For 2026: $24,500 employee elective deferral, $72,000 total annual additions limit (employee plus employer), $8,000 catch-up at age 50+, and an enhanced $11,250 catch-up for ages 60-63 under SECURE 2.0 | For 2026: $7,500 IRA contribution limit, with a $1,100 catch-up at age 50+ (the first year the IRA catch-up has been indexed) |
| Roth option | Commonly available inside the plan | Roth IRA, subject to income limits on direct contributions |
| Loan from the account | Permitted if the plan document allows, within statutory limits | Not permitted |
| Custodian required | No, the plan is trusteed, usually by you | Yes |
| Checkbook control | Built in | Only through a separate structure |
| Government filing | Form 5500-EZ once plan assets exceed the threshold, currently $250,000; confirm | None by you; custodian files |
| Ongoing administrative cost | Plan document maintenance and any filing | Custodial fees, often per asset or per transaction |
| Creditor protection | Varies; a plan covering only an owner and spouse is generally not an ERISA Title I plan, so protections differ from a standard 401(k) | Federal bankruptcy protection plus state law; Texas exemptions are strong |
| Debt-financed income | Potentially different treatment; see the next section, and do not assume | UDFI rules apply |
The creditor protection row is one people get backwards. The strongest federal protection is attached to plans covered by Title I of ERISA, and a plan covering only an owner and spouse generally is not one. Whether a solo 401(k) or an IRA is better protected in your state, in bankruptcy and outside it, is a question for an attorney, not for a comparison table.
The leverage tax difference
This section is the one to read slowly, because it contains the most overstated claim in this corner of the market.
The claim, as it usually appears, is that a solo 401(k) avoids unrelated debt-financed income on leveraged real estate while an IRA does not. There is something real underneath it. The Internal Revenue Code contains an exception, commonly cited as section 514(c)(9), under which certain qualified organisations, including qualified pension and profit-sharing plans, can hold debt-financed real property without the acquisition indebtedness producing unrelated debt-financed income. IRAs are generally not among the eligible entities. That asymmetry is genuine and it is why the question is worth asking.
Here is why the flat version of the claim is wrong, and why you should not act on it from a blog post, including this one.
The exception is conditional. It applies to acquisitions of real property and carries a list of requirements covering how the purchase price is determined, restrictions on seller financing and leasebacks, and limits on dealings with the seller. Fail a condition and the exception does not apply.
Partnership structures add requirements. Where the property is held through a partnership, further rules govern how income can be allocated among the partners before the exception is available.
A debt fund holds notes, not real property. Matador Note Fund 1 LLC makes first-lien loans secured by Texas real property. The fund's assets are mortgage notes. Whether an exception drafted around acquiring real property reaches a plan investor in a fund that lends against it is not obvious, and I am not going to resolve it for you in marketing copy.
Other UBTI can still arise. The exception, where it applies, addresses debt-financed income. It does not turn a plan into a blanket exemption from unrelated business taxable income generally.
The honest conclusion is a planning question, not an answer: if you are eligible for a solo 401(k) and you are considering a fund that may use leverage, the treatment of debt-financed income is a real potential difference between the two vehicles, worth putting to a qualified tax professional with the fund's documents in front of them, and worth getting in writing for your facts. Anyone who tells you it is settled is either simplifying or selling plan documents. The general UDFI framework is set out in our post on UBIT and UDFI.
Checkbook control
In a self-directed IRA, every transaction is an instruction. You sign a direction of investment, the custodian reviews the subscription package, the custodian signs as the subscribing entity, and the custodian wires. In a solo 401(k) you are the trustee, the plan's bank account is yours to operate, and you sign the subscription agreement and send the wire yourself.
The practical effect is time. A subscription that takes two or three weeks through a custodian can take two or three days. When a fund closes subscriptions on a fixed date, or when you want to be in for a quarter rather than after it, that difference is the difference between receiving a distribution and waiting three months for the next one.
The discipline it demands is the other half of the sentence, and it is rarely given equal billing.
Prohibited transaction rules apply in full, and there is no custodian left to notice. You cannot lend plan money to yourself, your spouse, your parents, your children or entities they control. You cannot invest plan assets in a deal you personally benefit from.
Separation is absolute. Plan money stays in the plan's account, titled in the name of the plan trust. No commingling, ever, including briefly.
You are now the recordkeeper. Investment documentation, annual valuations of illiquid assets, contribution records, and Form 5500-EZ when the threshold is crossed.
The plan document has to be maintained, including restatements on the provider's cycle.
A prohibited transaction can disqualify the plan, with tax consequences on the entire balance. That is the price of having removed the gatekeeper.
When an SDIRA is still the right answer
Often, and for unglamorous reasons.
No self-employment income. This is the decisive one, and no amount of structuring converts passive rental income into eligibility.
Inherited IRAs. They cannot be rolled into a solo 401(k), so they stay where they are.
You do not want to be a trustee. Some investors would rather pay a custodian a few hundred dollars a year than own the recordkeeping, the valuation paperwork and the filing. That is a rational purchase, not laziness.
One position, held for years. The speed advantage of checkbook control is worth a great deal to an investor funding loans directly and very little to an investor making a single subscription and holding it through a lock-up.
Cost, honestly compared. A solo 401(k) is not free. Between document provider fees, restatements and a possible filing, a plan with one investment can cost more than a flat-fee custodial IRA holding the same single position.
Getting it set up
The sequence, roughly:
Confirm eligibility with your CPA, in writing.
Obtain an employer identification number for the business and, where required, for the plan trust.
Adopt a written plan document. A prototype from a specialist provider is the usual route; confirm the document permits alternative investments, because many brokerage-sponsored documents do not.
Execute the adoption agreement and trust agreement, and name the trustee.
Open a bank or brokerage account titled in the name of the plan trust.
Move money in by direct trustee-to-trustee rollover, which is the slowest leg and is controlled by the institution releasing it.
Make any deferral elections within the plan's deadlines.
Then, and only then, direct investments.
Realistic timeline is weeks, not days, and the rollover dominates it. Establishment and contribution deadlines have changed in recent legislation, particularly around plans adopted after a year end, so confirm current deadlines rather than working from an older article.
Published provider schedules as of 2026 show solo 401(k) setup costs ranging widely by provider, from $0 at a handful of large no-frills platforms to $500-$1,500 for a custom prototype document drafted and filed by a third-party administrator, with annual maintenance typically $0 to $500 depending on the provider and whether assets are self-directed into alternatives. Self-directed IRA custodial fees, by comparison, typically run $200 to $500 a year flat, or 0.15% to 0.50% of account value under a value-based schedule — see the fee comparison in our self-directed IRA custodian guide for how those two models cross over.
Tax review status. This page is reviewed by a qualified tax professional before publication and annually thereafter, including an annual update of contribution limits. Reviewer: [REVIEWER NAME AND CREDENTIAL]. Last reviewed: [REVIEW DATE]. Next review due: [NEXT REVIEW DATE].
Frequently asked questions
Q: Can I use a solo 401(k) for private lending?
A: Generally yes, if the plan document permits alternative investments and the transaction does not involve a disqualified person. Many prototype plan documents from discount brokerages restrict investments to publicly traded securities, so the document controls. As trustee you would sign the subscription agreement and wire from the plan's account. The prohibited transaction rules apply in full and there is no custodian reviewing your instructions. Confirm your facts with a qualified professional.
Q: Who qualifies for a solo 401(k)?
A: A person with genuine self-employment income from a business that has no full-time employees other than the owner and a spouse. Certain employees can be excluded by the plan document, and the rules on long-term part-time workers have changed in recent years. Rental income and investment income are generally not self-employment income, which disqualifies many real estate investors who assume they are eligible. Eligibility is ongoing, not a one-time test.
Q: What is checkbook control?
A: The plan trustee, usually you, holds the plan's bank account and can fund an investment directly without routing an instruction through a custodian. It turns a multi-week subscription process into a same-week one. It also removes the last party who might catch a mistake, and it makes you responsible for recordkeeping, annual valuations, plan document maintenance and any required Form 5500-EZ filing.
Q: Is a solo 401(k) better than a self-directed IRA?
A: It is better on contribution capacity, transaction speed and often ongoing cost, for the narrow group of people eligible to have one. It is worse if you do not want to act as plan trustee, if you have no self-employment income, or if you are making a single buy-and-hold investment where speed does not matter. The tax treatment of debt-financed income is a real planning difference and one to confirm with a professional rather than assume.
If you are weighing the two vehicles for a subscription into this fund, book a call. I can tell you exactly what our subscription process requires from a plan trustee and from a custodian, which is the part your CPA will ask about.
Important disclosures. This article is for informational purposes only and is not an offer to sell or a solicitation of an offer to buy any security. Any offer is made only through the Private Placement Memorandum, Operating Agreement and Subscription Agreement of Matador Note Fund 1 LLC, which govern in all cases and should be read in full, including the risk factors. Interests are offered only to accredited investors as defined in Rule 501 of Regulation D, pursuant to Rule 506(c); accredited status must be independently verified. Real estate debt investments involve significant risk, including possible loss of principal. The 8% preferred return is non-cumulative and is payable only from available distributable cash at the manager's discretion; it is not guaranteed. The 8–12% figure is a target objective, not a promise or projection of results. Targeted returns are not guarantees of future performance, and past performance is not indicative of future results. Figures describing prior lending are the manager's own lending record and are not audited fund performance. Nothing here is legal, tax or investment advice. Matador Lending LLC is not a registered investment adviser.