SEP IRA vs Solo 401(k): 2026 Limits and Which to Pick

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By The Money Floor Editorial Team · Source-verified · Last updated October 2026

For 2026, a Solo 401(k) usually beats a SEP IRA if you work for yourself with no employees. As both employee and employer you can put in up to $24,500 as an employee deferral (IRS) plus an employer share, while a SEP IRA only takes the employer share. Both accounts share the same overall ceiling of $72,000 a year, and a Solo 401(k) adds catch-up contributions if you are 50 or older. The SEP IRA wins mainly on simplicity, or when you have employees. If you are self-employed with real income, this is one of the most important retirement choices you’ll make without an employer plan, because no one is doing it for you. Below is how each account works, with the 2026 IRS figures, so you can pick one and move on.

Before we go further: if you’re not sure whether to prioritize retirement savings or other financial goals right now, check out our guide on how to save for retirement when you have no 401k at work. It covers the bigger picture before you zoom in on a specific account type.

Option A: The SEP IRA

A SEP IRA (Simplified Employee Pension) is exactly what the name promises: simple. You open one at a brokerage like Fidelity or Vanguard, you contribute money, and you get a tax deduction. That’s mostly it. No annual IRS filings. No complex rules about employee vs employer contributions. Just a clean, functional retirement account built for self-employed people and small business owners.

How Much Can You Contribute to a SEP IRA in 2026?

For an employee, the 2026 SEP IRA limit is the lesser of 25% of compensation or $72,000, up from $70,000 in 2025, according to IRS Publication 560. If you are the self-employed owner, the same publication uses 20% of your net earnings from self-employment instead of 25%. The reason is that your own contribution is itself deducted when your compensation is figured, so the rate gets reduced. Net earnings are also figured after deducting half of your self-employment tax. Use the rate table and worksheets in Publication 560 chapter 5 to see exactly where you land.

Here’s what that looks like in practice. Say your net earnings from self-employment, after deducting half of your self-employment tax, come to $80,000. Twenty percent of $80,000 is $16,000. That’s your approximate SEP IRA contribution for the year. You deduct it from your taxable income, which is a real, meaningful tax break.

SEP IRA Pros

• Dead simple to open and maintain, with no annual IRS reporting (no Form 5500)
• High contribution limits compared to a regular IRA
• You can set one up and contribute up until your tax filing deadline, including extensions (October 15 for most people who file an extension)
• Works even if you have employees, though eligible employees must be covered under a written allocation formula that can’t favor highly compensated employees

SEP IRA Cons

• Roth treatment is not a given. Contributions are traditional (pre-tax) unless your plan allows a Roth SEP IRA, which Publication 560 says is permitted for tax years after 2022. Whether you can get one depends on the provider, so ask before you open an account
• No catch-up contributions for people 50 and over in a standard SEP IRA
• Lower effective contribution ceiling at lower incomes compared to a Solo 401k
• No loan provision, so you can’t borrow against it

Who the SEP IRA Is Best For

The SEP IRA fits people who want simplicity above all else. Freelancers, consultants, and side hustlers who earn good money but don’t want to deal with paperwork will find it easy to use, though it’s worth knowing how gig work and quarterly taxes factor into your overall self-employment tax picture. It also works well if you have employees, since the Solo 401k shuts that door entirely.

Option B: The Solo 401k

A Solo 401k (sometimes called an Individual 401k or Self-Employed 401k) is a traditional 401k adapted for self-employed people with no employees. It works exactly like the 401k you had at a corporate job, except you wear two hats. You contribute as the employee, and then you also contribute as the employer. That two-layer structure is what makes it so powerful.

How Much Can You Contribute to a Solo 401k in 2026?

The 2026 Solo 401(k) contribution limit follows the same $72,000 overall ceiling as the SEP IRA, according to the IRS. But the path to get there is very different. As the employee, you can defer up to $24,500 of your earned income in 2026, or 100% of it if you earn less than that. Then, as the employer, you can add a nonelective contribution on top. The IRS describes that employer share as up to 25% of compensation, with a special computation for self-employed people.

That structure matters enormously at lower income levels. The employee side is a flat amount you choose, up to $24,500, while a SEP IRA only gives you a percentage of earnings. Put your own net self-employment income into a Solo 401(k) calculator and a SEP IRA calculator and the gap between the two accounts becomes clear. The flat employee deferral is what drives the difference at lower and moderate incomes.

If you’re 50 or older, a plan that permits catch-up contributions lets you add $8,000 in 2026. If you are 60, 61, 62 or 63, the IRS sets a higher catch-up of $11,250 instead. Here is the arithmetic on the employee side alone, using the IRS 2026 figures: $24,500 + $8,000 = $32,500, or $24,500 + $11,250 = $35,750 at ages 60 to 63, before any employer contribution. The IRS counts catch-ups outside the overall limit, so the 2026 ceiling becomes $80,000, or $83,250 at ages 60 to 63. For late starters, this is a huge deal. Our catch-up savings guide for people at 35, 40, and 45 has more on making the most of these provisions.

Solo 401k Pros

• Higher effective contributions at lower and moderate incomes
• Roth deferrals are possible if your plan document includes them (Publication 560 describes the qualified Roth contribution program), so check the plan before you assume it
• Catch-up contributions for ages 50 and over, if the plan permits them
• Loan provision if your plan allows it: the IRS limit is 50% of your vested balance or $50,000, whichever is less
• More flexibility for tax planning if your plan offers both traditional and Roth deferrals

Solo 401k Cons

• More complex to set up and administer
• Once plan assets reach $250,000 or more at year end, the IRS generally requires an annual Form 5500-EZ filing
• The plan generally has to be adopted by the last day of the tax year to deduct that year’s contributions, though a newer rule gives sole proprietors with no employees extra time (see Deadlines and Paperwork below)
• It is built for an owner with no employees, or an owner and spouse. Hire an eligible employee and they must be included in the plan, which brings back nondiscrimination testing

Who the Solo 401k Is Best For

The Solo 401k is the right tool for self-employed people who want maximum contribution power and tax flexibility. Sole proprietors, single-member LLC owners, and independent contractors with no employees will get the most out of it. If you’re also interested in how HSA investing stacks up as a parallel tax-advantaged vehicle, our post on investing your HSA for the triple tax advantage is worth reading alongside this one.

SEP IRA vs Solo 401k: Side-by-Side

Which One Should You Choose?

Here’s the honest answer, broken down by situation.

Choose a Solo 401k if:

• You have no employees (other than a spouse)
• You want to put away a large amount at a modest income, since the flat employee deferral lets you save more than a percentage-only SEP IRA
• You’re 50 or older and want those catch-up contributions, an extra $8,000 per year in 2026 and $11,250 at ages 60 to 63
• You want Roth deferrals and your plan provider offers them
• You want the flexibility to switch between traditional and Roth deferrals depending on your income, if the plan allows both

To estimate your own Solo 401(k) total, start with the employee deferral you can afford, up to $24,500, then add the employer share using the Publication 560 worksheet for the self-employed. Run the same income through the SEP IRA math (20% of net earnings) and the difference between the two figures is the cost of choosing the simpler account. At modest incomes that gap can be large, especially if you’re starting late. Our retirement savings guide for late starters explains exactly why contribution levels matter so much when time is shorter.

Choose a SEP IRA if:

• You have employees (other than a spouse) who would have to be included in a Solo 401(k) and bring testing with them
• You want to set up your retirement account quickly with minimal friction
• You’re a high earner and the employer-only structure of the SEP IRA gets you close to the same $72,000 cap anyway (the math is in the section below)
• You found out about this after the tax year ended and want to set up something for that year. The IRS lets you set up a SEP as late as the due date of your return, including extensions (Publication 560)

What if you can only contribute a little right now?

Both accounts accept small contributions. There’s no required minimum. If you can only put in $100 a month ($1,200 a year), either account works fine. At that level, the Solo 401k’s higher ceiling doesn’t matter yet. What matters is starting. You can always switch or open the second account type later once your income grows.

IRS Publication 560 says you don’t have to make SEP contributions every year, so you’re never locked into a specific amount. That flexibility is helpful when income is variable, which it usually is when you’re self-employed.

For a broader look at the retirement plans available to self-employed people, start with the IRS overview of retirement plans for self-employed people.

What about both?

You generally can’t stack a SEP IRA and a Solo 401(k) for the same business to get two limits. Publication 560 says a SEP counts as a defined contribution plan, so your contributions to it are added to contributions to other defined contribution plans you maintain when the overall limit is tested. That limit is $72,000 in 2026. If you have a full-time job with a 401(k) and self-employment income on the side, you can maintain both a workplace 401(k) and a Solo 401(k). The IRS notes that employee deferral limits are per person, not per plan, so the total you defer across both can’t exceed $24,500 in 2026 (plus catch-up if you qualify). That’s a detail worth knowing before you assume you have two full limits to work with.

SEP IRA vs Solo 401(k) at Different Incomes

The easiest way to see the difference is to run each account’s own formula. For the SEP IRA, the owner’s contribution is 20% of net earnings from self-employment (Publication 560). Take hypothetical net earnings of $60,000. Twenty percent of $60,000 is $12,000. The Solo 401(k) employee side does not depend on a percentage: you can defer up to $24,500 as long as you earn at least that much, and that is before any employer contribution. Whether you can afford to defer that much from $60,000 is a cash flow question, but the account allows it.

At high incomes the gap closes. Dividing the $72,000 ceiling by the 20% rate gives $360,000 ($72,000 / 0.20), so a SEP IRA only reaches the cap at roughly $360,000 of net earnings. A Solo 401(k) gets to the same $72,000 ceiling at lower earnings because of the flat deferral, but it never goes higher. These are hypothetical figures to show the method, not a promise about your own numbers. Use the Publication 560 worksheet for your actual contribution.

Roth Options for Each Account

Both accounts can offer Roth treatment, but neither guarantees it. Under SECURE 2.0, Publication 560 says an employer’s SEP plan may allow a Roth SEP IRA for tax years after 2022. For a Solo 401(k), Roth deferrals depend on whether your plan document includes a qualified Roth contribution program. Provider support varies, so confirm Roth availability with the brokerage before you open anything if Roth matters to you.

Deadlines and Paperwork

A SEP can be set up for any year as late as the due date of your return, including extensions, and contributions are deductible if made by that date (Publication 560). Using the IRS model Form 5305-SEP also usually relieves you of annual plan information returns, per the same publication.

A Solo 401(k) has more moving parts. To deduct a year’s contributions, the plan generally has to be adopted by the last day of that year. Owner deferrals must be elected by the end of the tax year and can then be paid in by the return deadline, including extensions. A newer rule helps sole proprietors: for 2023 and later years, a sole proprietor with no employees can adopt a 401(k) after the end of the tax year, as long as the plan is adopted by the tax filing deadline without extensions. In that case the deferrals have to be paid in before that same filing deadline. The IRS wording covers sole proprietors, so if your business is taxed another way, ask your provider or a CPA how it applies. Once plan assets reach $250,000 or more at year end, the IRS generally requires an annual Form 5500-EZ.

What Happens When You Hire Someone

A Solo 401(k) is for a business owner with no employees, or the owner and spouse (IRS). The IRS says the no-testing advantage vanishes if you hire employees: eligible employees must be included in the plan, and their deferrals are subject to nondiscrimination testing unless the plan is a safe harbor plan or otherwise exempt. A SEP IRA keeps working with employees, but an eligible employee under the IRS definition in Publication 560 (age 21, worked for you in at least 3 of the last 5 years, and at least $800 of compensation in 2026) must be covered under a written allocation formula that does not favor highly compensated employees. If you plan to hire, factor that cost in before you choose.

What to Do This Week

Don’t let this decision sit. Here are the steps to take right now.

1. Figure out your approximate net self-employment income for 2026 so far. Multiply by 20% to get a rough SEP IRA contribution estimate. Then check whether a Solo 401(k)’s $24,500 employee deferral would let you contribute more.
2. If Solo 401(k) wins, open one at Fidelity or Vanguard before December 31. Adopting the plan by the last day of the tax year is the standard rule, and you can still fund it later.
3. If SEP IRA wins, or if it’s already past December 31, set up a SEP IRA by your tax filing deadline. The IRS allows setup as late as the due date of your return, including extensions.
4. If you’re not sure, set up the Solo 401(k) before year end. It keeps every option open, and you can always contribute a small amount and build from there.

Frequently Asked Questions

What is the difference between a SEP IRA and a Solo 401k?

A SEP IRA is an employer-only contribution account that’s simple to set up and maintain, with a 2026 limit of the lesser of 25% of compensation or $72,000 (for a self-employed owner, 20% of net earnings), per IRS Publication 560. A Solo 401(k) uses a two-layer contribution structure (employee plus employer), which allows higher contributions at lower income levels. It can also offer Roth deferrals if the plan includes them, and catch-up contributions for people 50 and over if the plan permits.

Which has higher contribution limits in 2026: SEP IRA or Solo 401k?

Both share the same overall ceiling of $72,000 in 2026, per the IRS. But the Solo 401(k) reaches that ceiling at lower income levels because the employee deferral of up to $24,500 is a flat amount, not a percentage of income. At moderate incomes the Solo 401(k) usually allows larger annual contributions than a SEP IRA at the same income. Catch-up contributions of $8,000 (or $11,250 at ages 60 to 63) are available in a Solo 401(k) that permits them and sit outside the overall limit.

Can I have both a SEP IRA and a Solo 401k?

Not in a way that gives you two limits for the same business. Per IRS Publication 560, a SEP counts as a defined contribution plan, so its contributions are added to your other defined contribution plan contributions when the overall $72,000 limit for 2026 is applied. If you have a day job with a 401(k) and a separate self-employment business, you can maintain a Solo 401(k) for the self-employment income. Just know the employee deferral limit of $24,500 in 2026 applies to you across all plans combined.

Can I open a Solo 401k if I have employees?

A Solo 401(k) is designed for a business owner with no employees, or an owner and spouse. Per the IRS, if you hire employees who meet the plan’s eligibility requirements, you must include them in the plan and their deferrals are subject to nondiscrimination testing unless the plan is exempt, so it stops being a simple solo plan. The SEP IRA does allow employees, though eligible employees must be covered under a written allocation formula that doesn’t favor highly compensated employees.

What is the deadline to open a Solo 401k for 2026?

To deduct 2026 contributions, the plan generally has to be adopted by December 31, 2026, per IRS Publication 560. A newer rule lets a sole proprietor with no employees adopt a 401(k) after year end, as long as the plan is adopted by the tax filing deadline without extensions. A SEP IRA is different: you can set it up for a year as late as the due date of your return, including extensions.

Is there a Roth option for a SEP IRA or Solo 401k?

Possibly for both, depending on the plan. IRS Publication 560 says a SEP plan may allow a Roth SEP IRA for tax years after 2022, and a Solo 401(k) can offer Roth deferrals if its plan document includes them. Provider support varies, so confirm Roth availability with the brokerage before you open an account.