Adam Bergman

Founder, Tax Lawyer, Author

I get asked some version of this question almost every week: which Solo 401(k) provider should I actually use? It’s a fair question, because the market is crowded and the providers are not interchangeable. Some are custodians who will hold your paperwork and little else. Some are administrators who understand the plan documents but outsource everything else. And a few, including my firm, try to do the whole job in house. If you’re comparing options, here’s what actually separates a good Solo 401(k) provider from one that will cost you time, money, or a compliance headache down the road.

What Is a Solo 401(k) Plan?

A Solo 401(k) is built for self-employed individuals and owner-only businesses, meaning you and, if applicable, your spouse are the only participants. It combines the high contribution limits of a traditional 401(k) with the investment freedom of a Self-Directed IRA, plus a couple of features neither one offers on its own: the ability to borrow from your own plan and, in most cases, a Roth option.

For 2026, the numbers look like this:

That enhanced catch-up bracket for savers aged 60 to 63 is new under SECURE 2.0, and it’s worth knowing about if you’re in that window and trying to maximize what you put away in your final working years.

One more 2026 wrinkle: if you’re 50 or older and your W-2 wages from your own business exceeded $150,000 in the prior year, your catch-up contributions have to go in as Roth, not pre-tax. That threshold is based on FICA wages from the same employer, so if your income comes mostly from self-employment on a Schedule C rather than a W-2 from an S-corp you run, it typically won’t apply to you. It’s a rule that trips up business owners who don’t have a provider watching for it, and a good Solo 401(k) provider should be flagging it for you before it becomes a problem.

Look at the Investment Options It Allows

Not every Solo 401(k) is self-directed in practice. A lot of providers, especially the ones attached to a big brokerage or bank, will set up your plan and then hand you a menu of the same stocks, bonds, and mutual funds you could have bought anywhere. That’s not a knock on those investments, but it defeats a lot of the reason people set up a Solo 401(k) in the first place. If you want to hold real estate, private equity, precious metals, or cryptocurrency inside your plan, confirm upfront that the provider actually supports it, and ask how the custody and reporting work in practice, not just whether it’s technically allowed.

Check Whether the Provider Offers a Roth Solo 401(k)

A Roth Solo 401(k) lets you contribute after-tax dollars in exchange for tax-free qualified withdrawals once you’ve held the account at least five years and reached age 59½. Depending on your income and where you expect your tax rate to land in retirement, that trade can be worth a lot. Roth accounts also sidestep Required Minimum Distributions during your lifetime, which matters if you’re trying to control your taxable income later in life. Not every provider offers a Roth option, and some that do offer it as an afterthought rather than a fully built-out feature, so ask specifically how their Roth Solo 401(k) is administered.

Make Sure Your Provider Actually Understands Tax Law

This is where I see people get burned the most. Setting up a Solo 401(k) isn’t just filling out a form, it’s establishing a qualified retirement plan governed by the IRS and ERISA. At some companies, the people drafting your plan documents aren’t tax attorneys or even tax professionals. They’re sales staff trained to process an application. That gap doesn’t show up on day one. It shows up two or three years later, when you’ve made an investment the plan document didn’t actually contemplate, or a loan that wasn’t structured correctly, and now you’re looking at a prohibited transaction. Ask directly who drafts and reviews your plan documents, and don’t accept a vague answer.

Ask About the Loan Option

Most Solo 401(k) plans allow you to borrow from your own account for any reason, which is one of the more underused features of this structure. The rules are straightforward:

• Maximum loan amount: the lesser of $50,000 or 50% of your account balance
• Repayment: at least quarterly, over a term of up to five years, at the Prime interest rate
• No credit check, no bank underwriting: since you’re borrowing from yourself, approval is fast and the interest you pay goes back into your own plan

Confirm your provider actually supports plan loans and can walk you through the documentation, since this is another area where a provider without in-house tax expertise tends to fall short.

Find Out Whether You Get Ongoing Support

A lot of providers are great at getting you set up and largely gone after that. The real test of a Solo 401(k) provider isn’t the sign-up process, it’s what happens in year two or three when you have a question about a new investment, a contribution calculation, or an IRS notice. Look for a provider with in-house staff who will still take your call once the account is open, not one that hands you off to a directory of outside accountants.

Confirm You’ll Have Checkbook Control

Checkbook control means you can make an investment by writing a check or wiring funds directly, without asking a custodian to sign off first. That’s a meaningful difference from a custodial-controlled plan, where every purchase or sale has to route through the custodian’s approval process, sometimes adding days or weeks to a transaction. If speed and flexibility matter to your investment strategy, real estate deals in particular, confirm the provider’s structure gives you actual checkbook control and not just marketing language that implies it.

Make Sure Plan Maintenance Isn’t Outsourced

Some providers set up your plan and then refer every follow-up question to a third-party accountant or attorney they don’t employ. That arrangement usually means slower answers, inconsistent advice, and an extra layer of cost. A provider with in-house professionals handling ongoing maintenance, including your annual IRS Form 5500-EZ where applicable, tends to give more consistent answers because the same team that built your plan is the one maintaining it.

Make Sure You Can Talk Directly to a Tax Professional

If your only point of contact is a salesperson or an account representative without specialized tax training, that’s a problem waiting to happen. You want direct access to someone who actually understands 401(k) plan rules well enough to answer a real question, not read a script. That access is what prevents a lot of the prohibited transaction issues I see happen after the fact, when a client made a decision based on bad information from someone who wasn’t qualified to give it.

Compare What You’ll Actually Pay

Fees vary more across Solo 401(k) providers than most people expect, and the difference isn’t always obvious until you’re a year or two in. Here’s how a few of the more commonly compared providers stack up as of this writing:

None of these providers charge an application fee, so the setup fee is really the number to compare. But it’s not the whole picture either. Setup buys you the plan document itself, so before you decide based on price alone, ask what’s actually included at that price, ongoing tax support, IRS Form 5500-EZ filing, loan document preparation, and Roth administration all vary by provider even when the upfront cost looks similar.

The IRA Financial Difference

I started IRA Financial in 2010 after spending a career as a tax attorney and running into this exact problem for a client: nobody could give her a straight answer about what she could actually do inside a Self-Directed IRA. I found the answer in the law library in about two hours, and it became clear the market needed a provider that treated this as tax law, not sales. That’s still how we run the Solo 401(k) side of the business. Setup is $999 for the first year and $399 annually after that, and it includes your adoption agreement, basic plan document, trust agreement, loan documents, and free tax and ERISA support from our in-house team, not an outside referral. We work with more than 27,000 clients across all 50 states, and our team includes in-house tax attorneys and ERISA specialists who are the people you’ll actually talk to if a question comes up.

Final Thoughts

None of this is complicated once you know what to look for, but it’s easy to miss if you’re comparing providers on price alone. Look at the investment flexibility, confirm the Roth and loan options actually exist rather than just being advertised, make sure checkbook control is real, and above all, make sure the people behind the plan understand tax law well enough to keep you out of trouble. Take the time to ask these questions before you sign up, not after, because a Solo 401(k) is a long-term relationship with whichever provider you choose, and the cheapest option upfront isn’t always the one that saves you money over time.

This content is for educational purposes only and does not constitute legal, tax, or investment advice. Consult a qualified professional before making any investment decisions.