Solo 401(k) for Self-Employed Individuals: 2026 Limits and Rules

A Solo 401(k) for a self-employed business owner with no full-time employees allows contributions of up to $72,000 in 2026, climbing as high as $83,250 with catch-up contributions for participants ages 60 through 63. The plan works like a standard employer 401(k), but because you are both the employee and the employer, you fund the account through two separate channels that stack on top of each other. That structure is why the ceiling sits so far above what a traditional IRA allows.

Who Qualifies

Two conditions have to be met. You need self-employment income from a legitimate business, and your business cannot have any full-time employees other than you and, if applicable, a spouse who works in the business. Sole proprietorships, single-member LLCs, partnerships, and S-corporation or C-corporation owners all qualify.¹

The IRS treats someone as a full-time employee once they work 1,000 or more hours in a year. Cross that threshold with any hire and you lose the solo classification, at which point you either bring the employee into the plan (subject to nondiscrimination testing) or move to a different plan type.¹ Part-time contractors and 1099 freelancers do not count as employees for this test.

2026 Contribution Limits

Contributions come from two sources:

Employee elective deferral of up to $24,500 of your earned income, the same deferral limit that applies to any 401(k) participant.²
Employer profit-sharing contribution of up to 25% of W-2 compensation if you are incorporated, or roughly 20% of net self-employment income if you are a sole proprietor or single-member LLC.
An aggregate cap of $72,000 for 2026 across both sources combined.³

Total contributions can never exceed your total net self-employment earnings for the year, no matter what the federal caps say.

Catch-Up Contributions at 50 and Older

If you turn 50 or older at any point during 2026, you can add an extra $8,000 on top of the $72,000 aggregate limit, bringing your maximum to $80,000.³

Enhanced Catch-Up for Ages 60 Through 63

SECURE 2.0 created a higher catch-up tier for participants who turn 60, 61, 62, or 63 during the tax year. For 2026, that enhanced catch-up is $11,250, which pushes the theoretical maximum to $83,250.⁴ Once you turn 64, you drop back to the standard $8,000 catch-up.

One wrinkle: if your wages from the business exceeded $145,000 in the prior calendar year, your catch-up contributions must be designated as Roth (after-tax). This mostly affects S-corporation owners paying themselves a W-2 salary above that threshold.⁴

How the Employer Contribution Works for Sole Proprietors

If you run an S-corporation or C-corporation, the calculation is direct: your employer profit-sharing contribution can be up to 25% of your W-2 wages. For a sole proprietor or single-member LLC taxed as a sole proprietorship, the effective rate is closer to 20% of net self-employment income, and the reason is worth understanding.

You start with gross revenue, subtract business expenses to get net profit, then subtract half of your self-employment tax. The 25% rate applies to that reduced figure. Because the contribution itself gets deducted from the base it is calculated on, the algebra lands near an effective 20% ceiling. This is the single most common mistake in funding a Solo 401(k). Basing the employer contribution on raw net profit will over-contribute and can trigger penalties.

Traditional and Roth Contributions

Most Solo 401(k) plans let you split contributions between traditional (pre-tax) and Roth (after-tax) buckets. Traditional contributions lower your taxable income now, grow tax-deferred, and are taxed as ordinary income on withdrawal. Roth contributions give you no upfront deduction, but qualified withdrawals in retirement come out completely tax-free, including growth.

Employer profit-sharing contributions historically had to go into a pre-tax account. SECURE 2.0 changed that, and plans that support the updated rules can now designate employer contributions as Roth.⁵ Not every provider has implemented this, so confirm before assuming it is available.

Setup, Deadlines, and Funding

Opening a Solo 401(k) means selecting a plan provider, completing an adoption agreement that spells out the plan’s rules, and establishing a brokerage or trust account to hold the investments. You will need an Employer Identification Number for the plan.¹

Timing is where owners trip up. The plan itself must be legally established by December 31 of the tax year you want to contribute for. Miss that date and the plan cannot be created retroactively for the prior year. Funding, though, runs on a different clock. Both employee deferrals and employer profit-sharing contributions can be deposited up to your business’s tax filing deadline, including extensions. For sole proprietors filing Schedule C, that is typically April 15, or October 15 with an extension. For S-corporations, it is March 15, or September 15 with an extension.

One nuance often missed: your written salary deferral election generally needs to be in place by December 31 of the year the deferrals apply to. The money can arrive later, but the paperwork documenting your intent should be signed before year-end.

Rolling Other Retirement Accounts In

A Solo 401(k) can accept rollovers from traditional IRAs, SEP-IRAs, other 401(k) plans, 403(b) plans, and governmental 457(b) plans.⁶ SIMPLE IRA funds can roll in as well, but only after you have participated in the SIMPLE plan for at least two years.

Designated Roth accounts from other plans, such as a Roth 401(k) or Roth 403(b), can roll into the Roth portion of your Solo 401(k) if your plan accepts them. Roth IRA funds cannot roll into a Solo 401(k) at all. Rollovers do not count against your annual contribution limits.

Loans From Your Solo 401(k)

If your plan document allows loans, you can borrow from your own account without triggering taxes or penalties. The maximum is the lesser of 50% of your vested account balance or $50,000.⁷ You repay yourself with interest, and payments feed back into the account.

The standard repayment window is five years, with payments due at least quarterly. If you use the loan to buy a primary residence, the five-year limit does not apply.⁷ Default on the loan or leave it outstanding past the deadline and the IRS treats the balance as a taxable distribution, which can also carry the 10% early withdrawal penalty if you are under 59½. Not every provider supports loans, so confirm the feature before choosing one.

Early Withdrawals Before Age 59½

Taking money out of your Solo 401(k) before age 59½ generally triggers a 10% additional tax on the taxable portion, on top of ordinary income tax.⁸ Several exceptions waive the 10% penalty:

Reaching age 59½.
Total and permanent disability.
A series of substantially equal periodic payments taken over your life expectancy, provided you stick with the schedule.
Separation from service during or after the year you turn 55.
Qualified birth or adoption distributions, up to $5,000 per child.
Federally declared disaster distributions, up to $22,000 for qualifying losses.

These exceptions only remove the 10% penalty. Traditional pre-tax distributions are still taxed as ordinary income regardless of your age.⁹

Required Minimum Distributions at 73

You must begin taking required minimum distributions from a Solo 401(k) once you reach age 73. Standard employer plans sometimes let non-owner employees delay RMDs until actual retirement, but that exception does not help Solo 401(k) participants because you are almost certainly a 5% or greater owner. The age-73 trigger applies whether or not you are still working.¹⁰

Roth 401(k) accounts are exempt from RMDs starting in 2024 under SECURE 2.0. If your entire balance sits in the Roth side of the plan, no forced distributions kick in at 73.

Prohibited Transactions

The IRS draws hard lines around what you can do with plan assets. A prohibited transaction is any deal between the plan and a disqualified person, which includes you, your spouse, your direct ancestors and descendants, and anyone who manages or advises the plan.¹¹

Common violations include using plan funds to buy property you will personally live in, lending plan money to yourself outside the formal loan rules, or having the plan purchase services from your own business. The plan also cannot invest in collectibles like art, antiques, gems, or certain coins.¹²

Consequences are severe. A disqualified person who engages in a prohibited transaction owes an excise tax on it, and in the worst case the IRS can disqualify the entire plan, making the full account balance taxable in the year of disqualification.¹¹ The trouble spot is usually the line between “the plan owns this asset” and “I’m personally benefiting from this asset,” especially in self-directed plans holding real estate or private investments.

Form 5500-EZ Once Assets Cross $250,000

If total assets in your Solo 401(k) exceed $250,000 at the end of the plan year, you must file Form 5500-EZ with the IRS. The threshold applies across multiple one-participant plans combined, and you file a separate 5500-EZ for each. You also file for the final plan year if you ever terminate the plan, regardless of the asset balance.¹³

The filing deadline is the last day of the seventh month after the plan year ends, which is July 31 for calendar-year plans. The penalty for missing it is $250 per day, up to $150,000 per plan year.¹³ Below $250,000 and outside a termination year, no filing is required.

1
Internal Revenue Service. One-Participant 401(k) Plans
2
Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026
3
Internal Revenue Service. Notice 2025-67 – 2026 Limitations Adjusted as Provided in Section 415(d)
4
Federal Register. Catch-Up Contributions
5
Internal Revenue Service. SECURE 2.0 Act Changes Affect How Businesses Complete Forms W-2
6
Internal Revenue Service. Rollover Chart
7
Internal Revenue Service. Retirement Topics – Plan Loans
8
Office of the Law Revision Counsel. 26 USC 72 – Annuities; Certain Proceeds of Endowment and Life Insurance Contracts
9
Internal Revenue Service. Retirement Topics – Exceptions to Tax on Early Distributions
10
Internal Revenue Service. Retirement Plan and IRA Required Minimum Distributions FAQs
11
Internal Revenue Service. Retirement Topics – Prohibited Transactions
12
Internal Revenue Service. Retirement Plan Investments FAQs
13
Internal Revenue Service. Instructions for Form 5500-EZ