Solo 401(k) for Self-Employed Explained

November 5, 2026 Invest Clarity Path Team

Short answer: A solo 401(k) is a 401(k) plan for a self employed person with no full time employees, other than a spouse who also works in the business. The IRS calls it a one participant 401(k). It lets you contribute in two roles at once, as the employee and as the employer, so the total you can put in is much higher than an IRA alone. For the 2026 tax year, you can defer up to 24,500 dollars as the employee, plus an employer contribution of up to 25 percent of compensation, with a combined limit of 72,000 dollars before any catch up contribution. If you are age 50 or older, you can add a catch up contribution of 8,000 dollars, or 11,250 dollars if you turn 60, 61, 62, or 63 during 2026.

If you work for yourself, you do not have an employer to offer you a 401(k). A solo 401(k) fills that gap. This article explains who qualifies, how the two contribution buckets work, the 2026 limits, and the deadlines, in plain English.

What is a solo 401(k)?

A solo 401(k) is a retirement plan for a business owner who has no employees. It is also called an individual 401(k) or a self employed 401(k). The IRS name for it is a one participant 401(k) plan. It works like a regular 401(k), but you sit on both sides of the table. As the employee, you defer part of your own pay into the plan. As the employer, your business makes an extra profit sharing contribution on top.

That two sided design is what makes the solo 401(k) powerful. An IRA for 2026 allows up to 7,500 dollars, or 8,600 dollars if you are age 50 or older. A solo 401(k) allows far more, because the employer contribution is added to your employee deferral, up to a combined limit of 72,000 dollars for 2026.

Who can open a solo 401(k)?

You can open a solo 401(k) if you are self employed and you have no full time employees, other than yourself and your spouse. The IRS allows one exception to the no employees rule. Your spouse can take part in the plan if your spouse earns income from your business.

You qualify if you earn self employment income, whether you are a sole proprietor, a freelancer, a consultant, an independent contractor, or the owner of a single member limited liability company. Owners of partnerships and S corporations can also qualify, as long as they have no employees other than a spouse. The type of business entity changes how the employer contribution is worked out, which is explained below, but it does not change the basic idea.

The two contribution buckets

A solo 401(k) has two buckets, and understanding them is the key to the whole plan.

Bucket 1: Employee elective deferral

As the employee, you can defer part of your pay into the plan, either pre tax or Roth, depending on what your plan allows. For 2026, the employee deferral limit is 24,500 dollars, or 100 percent of your compensation, whichever is less. You can defer the full 24,500 dollars even if your income is modest, as long as your compensation covers it. This deferral limit applies per person, not per plan, so it includes any deferral you make to another employer’s 401(k) in the same year.

Bucket 2: Employer profit sharing contribution

As the employer, your business can make an extra profit sharing contribution on top of your deferral. The general rule is up to 25 percent of compensation. The exact calculation depends on your business type.

For an S corporation or C corporation owner, the employer contribution is up to 25 percent of your W-2 wages. Distributions you take from the business do not count. Only your salary counts.

For a sole proprietor, a partnership, or a single member limited liability company taxed as a disregarded entity, the calculation is different. The IRS Publication 560 worksheet starts with your net self employment income, subtracts half of your self employment tax, and then applies the percentage in a way that works out to about 20 percent of that net figure. The maths is circular, which is why most people let their tax software or their plan provider work it out, rather than doing it by hand. The important point is that the employer contribution for a sole proprietor is roughly 20 percent of net self employment income, not a straight 25 percent.

The combined limit

The two buckets together cannot exceed the overall limit for defined contribution plans. For 2026, that limit is 72,000 dollars, before any catch up contribution. Your total cannot exceed 100 percent of your compensation either. Whichever is lower, the 72,000 dollar cap or your compensation, is the ceiling.

The 2026 solo 401(k) limits

All figures in this section are for the 2026 tax year, verified against the IRS on 5 November 2026. The source is IRS News Release IR-2025-111 and Notice 2025-67, published in Internal Revenue Bulletin 2025-49, plus the IRS page on 401(k) and profit sharing plan contribution limits.

Employee elective deferral: 24,500 dollars in 2026, up from 23,500 dollars in 2025.
Catch up contribution for age 50 or older: 8,000 dollars in 2026, up from 7,500 dollars in 2025. That takes the employee total to 32,500 dollars.
Higher catch up for ages 60, 61, 62, and 63: 11,250 dollars in 2026 instead of 8,000 dollars, under a change from the SECURE 2.0 Act. That takes the employee total to 35,750 dollars for those ages.
Overall combined limit, employee plus employer: 72,000 dollars in 2026, up from 70,000 dollars in 2025. With the standard catch up, the total can reach 80,000 dollars. With the higher ages 60 to 63 catch up, it can reach 83,250 dollars.
Compensation limit: 360,000 dollars in 2026, up from 350,000 dollars in 2025. This is the maximum amount of pay that can be taken into account when working out contributions.
Employer contribution: up to 25 percent of compensation, or about 20 percent of net self employment income for a sole proprietor, as explained above.

Worked example: an S corporation owner in 2026

This is an illustration with round numbers, using the verified 2026 limits. Sara runs a small design business as an S corporation. She pays herself a W-2 salary of 80,000 dollars in 2026, and she has no employees other than herself. She is 45 years old, so no catch up contribution applies.

As the employee, Sara defers 24,500 dollars into her solo 401(k), the full 2026 limit. Her salary of 80,000 dollars is more than the deferral, so the 100 percent of compensation rule does not cut it down. As the employer, her business can contribute up to 25 percent of her W-2 salary. That is 25 percent of 80,000 dollars, which is 20,000 dollars. Her total contribution is 24,500 dollars plus 20,000 dollars, which is 44,500 dollars. That is well below the overall 2026 limit of 72,000 dollars, so the cap does not bind her.

Now change one number. Suppose Sara pays herself a salary of 200,000 dollars instead. Her employee deferral is still 24,500 dollars, because that limit is fixed. Her employer contribution would be 25 percent of 200,000 dollars, which is 50,000 dollars. The total would be 74,500 dollars, but the overall limit for 2026 is 72,000 dollars, so her total is cut back to 72,000 dollars. The employer piece is reduced first, to 47,500 dollars, so the total is exactly 72,000 dollars. That is how the cap works in practice.

How to set up a solo 401(k), step by step

Step 1: Confirm you qualify. You need self employment income and no full time employees other than your spouse. If you are not sure, read the IRS page on one participant 401(k) plans before you start.

Step 2: Choose a provider. Compare providers on fees, investment choice, whether a Roth option is offered, whether loans are allowed, and whether the provider handles the yearly paperwork. This article does not recommend any specific provider. Read the fee schedule and the plan document before you sign.

Step 3: Adopt the plan by 31 December 2026 for a 2026 plan. You must sign the plan documents before the year ends, even if you fund the employer part later. This deadline is strict, so do not leave it to the last week of December.

Step 4: Open the account and make your employee deferral by 31 December 2026. Your deferral must be in the plan by the end of the year.

Step 5: Make the employer contribution by your tax filing deadline, including extensions. For a 2026 plan, that is usually 15 April 2027, or later if you file an extension.

Step 6: Keep records and file the yearly form. A solo 401(k) with assets over 250,000 dollars must file IRS Form 5500-EZ each year. Even below that threshold, keep records of every contribution, split between employee and employer, so you can prove the amounts later.

Common mistakes to avoid

The most common mistake is missing the 31 December deadline to adopt the plan. You cannot set up a 2026 solo 401(k) in 2027. The second mistake is deferring more than 24,500 dollars across all your 401(k) plans in 2026, because the limit is per person, not per plan. The third mistake is working out the employer contribution on the wrong figure, such as using business distributions instead of W-2 wages for an S corporation, or using gross revenue instead of net self employment income for a sole proprietor. The fourth mistake is forgetting the Form 5500-EZ filing once the plan balance passes 250,000 dollars. The fifth mistake is hiring a full time employee and keeping the solo 401(k) running, which breaks the one participant rule. The sixth mistake is using 2025 figures for a 2026 contribution. The 2026 limits are 24,500 dollars for the deferral and 72,000 dollars overall, not the 2025 figures of 23,500 dollars and 70,000 dollars.

How a solo 401(k) fits into a wider plan

A solo 401(k) is usually the main retirement account for a self employed person, but it does not have to be the only one. You can also hold a Roth IRA, subject to its own income limits and the 7,500 dollar limit for 2026. To understand how retirement accounts fit together, see: What Is a Retirement Account, in Simple Terms?

If you also earn side income, keep it tracked separately, because your side income can affect your tax position and your contribution calculations. See: How Do I Track Side Income for Tax in Simple Terms? For the wider order of retirement saving, including how much to put away and when, see: Financial Planning for Retirement And for the simple way to start investing the money once it is inside the account, see: What Is an Index Fund and Why Do Beginners Use It?

FAQ

Who qualifies for a solo 401(k)?

A self employed person with no full time employees, other than a spouse who earns income from the business. You can be a sole proprietor, freelancer, consultant, independent contractor, or the owner of a single member limited liability company, partnership, or S corporation.

How much can I contribute to a solo 401(k) in 2026?

As the employee, you can defer up to 24,500 dollars. As the employer, your business can add up to 25 percent of compensation, or about 20 percent of net self employment income for a sole proprietor. The combined total cannot exceed 72,000 dollars for 2026, before any catch up contribution.

What is the catch up contribution for 2026?

If you are age 50 or older, you can add 8,000 dollars, taking the employee total to 32,500 dollars and the overall total to 80,000 dollars. If you turn 60, 61, 62, or 63 during 2026, the catch up is 11,250 dollars instead, taking the overall total to 83,250 dollars.

What is the deadline to set up a solo 401(k) for 2026?

The plan must be adopted by 31 December 2026, and your employee deferral must be made by the same date. The employer contribution can be made later, up to your tax filing deadline, usually 15 April 2027, or later if you file an extension.

Can my spouse join my solo 401(k)?

Yes, if your spouse earns income from your business. Your spouse can make their own employee deferral and receive their own employer contribution, subject to their own limits. That can raise the total a household can put away.

Can I have a solo 401(k) and a 401(k) at a day job?

Yes, but the employee deferral limit of 24,500 dollars for 2026 applies across all your 401(k) plans together, not to each plan separately. The employer contribution to your solo 401(k) is separate, and it is limited by your self employment income and the 72,000 dollar overall cap for that plan.

Conclusion

A solo 401(k), which the IRS calls a one participant 401(k), is a 401(k) plan for a self employed person with no full time employees other than a spouse. It lets you contribute as both the employee and the employer. For the 2026 tax year, the employee deferral limit is 24,500 dollars, the catch up contribution is 8,000 dollars for age 50 or older, or 11,250 dollars for ages 60 to 63, and the overall combined limit is 72,000 dollars, before any catch up. The employer contribution is up to 25 percent of compensation, or about 20 percent of net self employment income for a sole proprietor, and compensation counted for the calculation is capped at 360,000 dollars for 2026. The plan must be adopted by 31 December 2026, the employee deferral must be made by the same date, and the employer contribution can be made by your tax filing deadline. You can read the official limits in the IRS News Release IR-2025-111, 401(k) limit increases to $24,500 for 2026, IRA limit increases to $7,500 and the IRS page on 401(k) and profit-sharing plan contribution limits.

This article is for general information and education only. It is not legal or financial advice.