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Being self-employed offers flexibility, independence, and the opportunity to build a business. However, it also means taking responsibility for your own retirement savings.

Unlike traditional employees, freelancers, independent contractors, and business owners may not have access to an employer-sponsored retirement plan. They must choose an account that fits their income, business structure, and long-term financial goals.

Two popular options in the United States are the Solo 401(k) and the SEP IRA.

Both retirement plans can help self-employed individuals save for retirement while potentially receiving valuable tax advantages. However, they work differently. A Solo 401(k) allows an eligible business owner to contribute in both an employee and employer capacity, while a SEP IRA relies on employer contributions.

Understanding these differences is important because the right plan can affect how much you save, how you manage taxes, and whether you can provide retirement benefits to employees.

In this guide, we compare Solo 401(k) vs. SEP IRA rules, 2026 contribution limits, eligibility requirements, tax treatment, withdrawal rules, and administrative responsibilities. We also explain which option may make sense for freelancers, independent contractors, and small business owners.

What Is a Solo 401(k)?

A Solo 401(k), also called an individual 401(k) or one-participant 401(k), is a retirement plan designed for a business owner who has no eligible common-law employees other than a spouse.

It follows many of the same basic rules as a traditional employer-sponsored 401(k). However, the business owner effectively fills two roles:

• Employee
• Employer

This structure creates an important advantage. The owner may contribute as an employee through elective deferrals and also make employer contributions based on business earnings.

For example, a self-employed consultant may be able to contribute part of their eligible earnings as an employee and make an additional profit-sharing contribution through the business.

A Solo 401(k) can be particularly useful for:

• Freelancers
• Independent contractors
• Consultants
• Sole proprietors
• One-person LLC owners
• Certain owner-only corporations
• Business owners whose only employee is their spouse

The plan generally cannot remain a true one-participant plan if the business hires eligible employees other than the owner and spouse. Certain employees may need to be included under retirement plan eligibility rules.

How Solo 401(k) Contributions Work

The most important feature of a Solo 401(k) is the ability to contribute in two capacities.

1. Employee elective deferrals

The business owner can defer eligible compensation into the plan, subject to the annual IRS limit and the applicable compensation rules.

2. Employer contributions

The business can make an additional contribution based on the owner’s compensation or self-employment earnings.

The combined contributions are subject to an overall annual limit.

This two-part structure can allow eligible business owners to save more than they could through an IRA alone.

What Is a SEP IRA?

A SEP IRA, or Simplified Employee Pension Individual Retirement Arrangement, is an employer-sponsored retirement arrangement designed to provide a relatively straightforward way for businesses to contribute toward retirement savings.

It is available to many types of businesses, including:

• Sole proprietorships
• Partnerships
• LLCs
• Corporations
• Freelancers
• Independent contractors
• Small businesses with eligible employees

Unlike a Solo 401(k), a SEP IRA does not allow the business owner to make employee salary-deferral contributions under the SEP arrangement.

Instead, the business makes employer contributions to SEP IRA accounts for eligible participants.

For a self-employed individual, the contribution is calculated using special IRS rules based on net earnings from self-employment.

How SEP IRA Contributions Work

A business owner decides whether to make a contribution for a particular year, subject to the plan rules and applicable deadlines.

When contributions are made, the business generally must apply the same contribution percentage to the compensation of all eligible employees.

For example, if the business contributes 10% of eligible compensation for the owner, it generally must contribute 10% for each eligible employee.

This requirement is important. A SEP IRA may be easy to establish, but it can become more expensive when a business has multiple eligible employees.

Unlike a Solo 401(k), a SEP IRA does not provide a separate employee elective-deferral contribution or an age-based SEP catch-up contribution.

Solo 401(k) vs. SEP IRA: Key Differences

Both plans can help self-employed individuals build retirement savings. However, their contribution structures and administrative requirements are different.

Feature	Solo 401(k)	SEP IRA
Main users	Owner-only businesses, generally with no eligible employees other than a spouse	Self-employed individuals and businesses with employees
Employee contributions	Yes	No employee salary deferrals
Employer contributions	Yes	Yes
2026 employee deferral limit	$24,500	Not available
2026 overall defined contribution limit	Generally $72,000, excluding catch-up contributions	Generally $72,000
Catch-up contributions	Available if plan permits	Not available under the SEP contribution formula
Eligible employees	Generally cannot operate as an owner-only plan once eligible common-law employees are covered	Eligible employees generally must receive the same contribution percentage
Roth option	Depends on plan terms and provider	Roth SEP contributions may be available if the plan supports them
Loans	May be permitted if the plan allows	Generally not available
Administration	More plan administration than a basic SEP IRA	Usually simpler
Employer contribution flexibility	Depends on plan design and applicable rules	Contributions are generally discretionary each year, subject to plan terms

The most important distinction is the contribution structure.

A Solo 401(k) gives an eligible owner the opportunity to contribute as both employee and employer. A SEP IRA relies on employer contributions.

Consequently, the Solo 401(k) may be more attractive for an owner with no eligible employees who wants to maximize retirement savings. A SEP IRA may be easier for a business owner who values simpler administration or needs a plan that can cover employees.

2026 Solo 401(k) Contribution Limits

Contribution limits are one of the most important considerations when comparing retirement plans.

For tax year 2026, the basic employee elective-deferral limit for most 401(k) plans is $24,500.

However, the total amount you can contribute to a Solo 401(k) may be higher because employer contributions are also allowed.

1. Employee Elective Deferrals

For 2026, eligible participants can generally defer up to:

• $24,500 for individuals under age 50
• An additional $8,000 for eligible participants age 50 or older
• An additional $11,250 instead of $8,000 for eligible participants age 60, 61, 62, or 63, if the plan permits the higher catch-up contribution

These limits are subject to applicable compensation and plan requirements.

The elective-deferral limit is generally shared across your 401(k) and certain other employer retirement plans.

For example, if you contribute $15,000 to a 401(k) through an unrelated employer during 2026, you generally have only $9,500 of the standard $24,500 elective-deferral limit remaining for your Solo 401(k).

You cannot simply claim the full employee deferral limit separately under every plan.

2. Employer Contributions

A Solo 401(k) also allows the business to make employer contributions.

The calculation depends on your business structure and compensation.

For a self-employed individual operating as a sole proprietor, the calculation is more complicated than simply taking 25% of gross business revenue.

The IRS generally uses net earnings from self-employment after accounting for the deductible portion of self-employment tax and the contribution itself.

For many self-employed individuals, the effective maximum employer contribution is calculated using a special rate that is generally equivalent to 20% of adjusted net earnings.

Corporations and other business structures may use different compensation calculations.

3. Overall Contribution Limit

For 2026, the general annual defined contribution limit is $72,000, excluding catch-up contributions.

The overall limit generally applies to the combined employee and employer contributions, subject to the applicable compensation limit.

For eligible participants, catch-up contributions may be added above the standard annual additions limit.

This means an individual under age 50 cannot automatically contribute $72,000 just because that number is the IRS limit. The actual amount depends on eligible compensation and the business’s contribution calculation.

2026 SEP IRA Contribution Limits

The SEP IRA contribution limit for 2026 is generally the lesser of:

• 25% of eligible compensation, or
• $72,000.

The compensation limit used to calculate contributions is $360,000 for 2026.

However, self-employed individuals must use a special calculation.

SEP IRA Contributions for Self-Employed Individuals

A sole proprietor cannot simply multiply gross business revenue by 25%.

Instead, the calculation generally starts with net profit and accounts for the deductible portion of self-employment tax.

Because the contribution itself also affects the calculation, the effective maximum contribution rate for many self-employed individuals is generally 20% of adjusted net earnings.

Consider this simplified illustration:

A freelancer has $100,000 in net business profit before the relevant self-employment tax adjustment and retirement contribution calculation.

The SEP IRA contribution is not automatically $25,000.

The freelancer must calculate adjusted net earnings using the applicable IRS worksheet and rules.

The same special calculation is relevant when determining the owner’s employer contribution under a Solo 401(k).

SEP IRA Contributions for Employees

When a business has eligible employees, the employer must follow SEP eligibility rules.

The standard maximum eligibility requirements generally include:

• The employee is at least 21 years old.
• The employee has worked for the employer in at least three of the previous five years.
• The employee has received at least $800 in compensation from the employer during 2026.

Employers may use less restrictive eligibility requirements.

Certain employees, such as those covered by qualifying collective bargaining agreements or nonresident aliens without applicable US wages, may be excluded under the rules.

If an employee qualifies, the employer generally must contribute the same percentage of compensation used for other eligible participants.

This is a major consideration for businesses with multiple employees.

Example: How Much Could You Contribute to Each Plan?

Let’s compare two self-employed professionals.

Both operate small businesses and have enough eligible earnings to make meaningful retirement contributions.

Example A: Self-Employed Consultant

A consultant operates a one-person business with no eligible employees other than a spouse.

The consultant wants to save as much as reasonably possible for retirement.

A Solo 401(k) may provide two contribution opportunities:

• Employee elective deferrals
• Employer profit-sharing contributions

The consultant can potentially use both, subject to the annual limits and self-employment calculation.

Example B: Small Business Owner With Employees

A business owner has several employees who meet SEP IRA eligibility requirements.

The owner wants a relatively simple retirement arrangement.

A SEP IRA may be attractive because the employer can make contributions without setting up employee salary-deferral arrangements.

However, the owner must account for the contributions required for eligible employees.

The cost of employee contributions may influence whether the SEP IRA is appropriate.

Comparison at a Glance

Situation	Potentially Suitable Plan	Main Consideration
Freelancer with no eligible employees	Solo 401(k)	Employee plus employer contributions
Independent contractor with variable income	Either	Contribution flexibility and administrative preferences
Sole proprietor with high earnings	Solo 401(k)	Potential to use both contribution types
Small business with eligible employees	SEP IRA or another employer plan	Employee contribution obligations
Business owner who wants simpler administration	SEP IRA	Generally simpler plan structure
Owner who wants plan loans	Solo 401(k), if permitted	Plan terms and loan restrictions
Owner interested in Roth salary deferrals	Solo 401(k), if permitted	Roth features and plan availability

The correct choice depends on more than the headline contribution limit.

You should also consider the cost of covering employees, business structure, plan fees, investment options, and tax strategy.

Tax Advantages: Solo 401(k) vs. SEP IRA

Both retirement plans can provide tax advantages, but the treatment depends on the type of contribution and the plan’s features.

Traditional Solo 401(k) Tax Treatment

Traditional employee elective deferrals are generally made on a pretax basis.

This means eligible contributions can reduce current federal taxable income, subject to the applicable tax rules.

Investment earnings generally grow tax-deferred.

Withdrawals are generally included in taxable income when distributed, unless an exception or special tax treatment applies.

Employer contributions are also generally deductible by the business, subject to applicable rules.

Roth Solo 401(k) Tax Treatment

Some Solo 401(k) plans allow Roth employee elective deferrals.

Roth contributions are made with after-tax money, meaning they do not generally reduce current taxable income.

However, qualified Roth distributions can be tax-free if the applicable requirements are satisfied.

Not every plan provider offers Roth features, so review the plan document before opening an account.

SEP IRA Tax Treatment

Traditional SEP IRA contributions are generally made by the employer and are generally deductible by the business, subject to applicable tax rules.

Investment earnings generally grow tax-deferred.

Distributions are generally taxable as ordinary income, except to the extent that special rules apply.

SECURE 2.0 also permits certain SEP arrangements to offer Roth employer contributions if the plan supports them and applicable requirements are satisfied.

However, Roth SEP availability is not universal. Confirm the plan’s features with the provider.

Which Plan Offers Better Tax Benefits?

Neither plan is automatically better for everyone.

A traditional Solo 401(k) may provide more flexibility because it can allow both pretax and Roth employee deferrals.

A traditional SEP IRA can provide deductible employer contributions without requiring employee salary deferrals.

Your current tax bracket, expected retirement tax bracket, business earnings, and contribution goals all matter.

The Pro-Rata Rule and SEP IRA Considerations

One important issue deserves attention if you are considering a SEP IRA and also want to use a backdoor Roth IRA strategy.

Traditional SEP IRA balances generally count toward the IRA pro-rata calculation when determining the taxable portion of a Roth conversion.

This can create an unexpected tax bill.

For example, imagine that you have:

• $90,000 in a traditional SEP IRA
• $10,000 in nondeductible traditional IRA contributions

If you convert $10,000 to a Roth IRA, you generally cannot simply treat the entire conversion as coming from the nondeductible contribution.

The IRS generally calculates the taxable and nontaxable portions using the combined value of applicable traditional, SEP, and SIMPLE IRAs at year-end, together with relevant distributions and conversions during the year.

A Solo 401(k) balance is generally not included in the IRA pro-rata calculation.

However, whether you can roll eligible IRA money into a Solo 401(k) depends on the plan document and applicable rollover rules.

This distinction can be important for high-income self-employed individuals who use backdoor Roth IRA strategies.

Do not assume that opening a SEP IRA will have no effect on your other retirement accounts.

Can You Have Both a Solo 401(k) and a SEP IRA?

In some situations, a person may participate in more than one retirement plan.

However, having multiple accounts does not automatically give you separate contribution limits for every plan.

The rules depend on whether the plans are maintained by the same employer or related employers, how contributions are classified, and whether the individual has other retirement plan participation.

For example, the employee elective-deferral limit is generally shared across applicable 401(k) plans.

The overall annual additions limit also applies under relevant plan aggregation rules.

If you operate multiple businesses, the rules can become more complicated because controlled-group and affiliated-service-group rules may apply.

Before opening both plans, determine whether the businesses are treated as related employers for retirement plan purposes.

A tax professional or qualified retirement plan administrator can help evaluate the arrangement.

Withdrawal Rules: What Happens When You Need the Money?

Retirement plans are designed for long-term savings, so withdrawing money early can create taxes and penalties.

Solo 401(k) Withdrawals

Traditional Solo 401(k) distributions are generally taxable as ordinary income.

Withdrawals before age 59½ may also trigger a 10% additional tax unless an exception applies.

Certain plans allow participant loans, but loans are not mandatory features.

If your plan permits loans, the amount and repayment terms must follow applicable rules.

A Solo 401(k) loan can provide access to money without treating the loan as a taxable distribution when properly structured. However, missed repayments or other failures can cause the loan to become a taxable distribution.

SEP IRA Withdrawals

SEP IRA withdrawals generally follow traditional IRA distribution rules.

Distributions are generally taxable as ordinary income.

Withdrawals before age 59½ may be subject to the 10% additional tax unless an exception applies.

Unlike some Solo 401(k) plans, SEP IRAs generally do not allow participant loans.

This means a SEP IRA may offer less flexibility if you want access to retirement funds before retirement age.

Required Minimum Distributions

Traditional retirement accounts are generally subject to required minimum distribution rules.

For many individuals, required minimum distributions begin at age 73 under current law.

Roth 401(k) accounts are not subject to lifetime required minimum distributions for the original account owner under current rules.

Roth IRAs also generally do not require lifetime distributions for the original owner.

The exact treatment depends on account type, beneficiary status, and applicable tax rules.

Which Plan Is Easier to Set Up and Maintain?

Administrative complexity can influence your decision.

A SEP IRA is generally simpler to establish and maintain.

A business owner typically completes the required plan documentation, establishes SEP IRA accounts for eligible participants, and makes contributions when appropriate.

A Solo 401(k) involves more plan administration.

Depending on the plan design, you may need to manage:

• Plan documents
• Employee deferral elections
• Employer contributions
• Contribution records
• Loan provisions, if offered
• Plan compliance
• Required reporting

For example, a one-participant 401(k) plan generally must file Form 5500-EZ when plan assets reach the applicable reporting threshold, generally $250,000 at the end of the plan year, or when the plan is terminated with final assets.

Special reporting rules and exceptions may apply.

A SEP IRA generally does not have the same annual Form 5500 filing requirement for a basic arrangement.

However, simpler administration does not mean there are no responsibilities. Employers must still follow the SEP document, eligibility, contribution, and disclosure requirements.

Important Deadlines for Solo 401(k) and SEP IRA Contributions

Contribution deadlines can differ depending on the plan and the type of contribution.

Solo 401(k) Deadlines

Employee elective deferrals and employer contributions may have different timing requirements.

The business generally needs to establish the plan and complete applicable deferral elections within the required period.

Employer contributions may generally be made by the business tax-filing deadline, including extensions, depending on the plan and applicable rules.

Do not assume that you can wait until you file your tax return to establish a plan and make every type of contribution.

SEP IRA Deadlines

SEP IRA contributions can generally be made by the business tax-filing deadline, including extensions.

This flexibility can be useful for self-employed individuals who need additional time to calculate their final business income and retirement contribution.

However, the contribution must follow the plan’s terms and applicable employee eligibility rules.

Always verify the deadline for your specific business structure and tax year.

How to Choose Between a Solo 401(k) and SEP IRA

The right choice depends on your income, employees, retirement goals, and willingness to manage plan administration.

Use the following considerations to narrow down your options.

Choose a Solo 401(k) If:

• You operate an owner-only business with no eligible employees other than a spouse.
• You want to contribute as both employee and employer.
• You want the option of Roth employee deferrals.
• You want a retirement plan that may allow participant loans.
• You want to maximize contributions based on your eligible business earnings.
• You are comfortable handling additional plan administration.

A Solo 401(k) can be particularly attractive when your business has strong profits and you want to build retirement savings aggressively.

Choose a SEP IRA If:

• You want a relatively simple retirement plan.
• You do not need employee salary-deferral contributions.
• Your business income changes from year to year.
• You want to make discretionary employer contributions.
• You have employees and are prepared to contribute for eligible participants.
• You prefer a plan with fewer administrative responsibilities.

A SEP IRA can be useful for businesses that want to provide retirement contributions without setting up a traditional salary-deferral plan.

Consider Other Retirement Plans Too

A Solo 401(k) and SEP IRA are not the only options.

Depending on your business and employees, you may also consider:

• SIMPLE IRA
• Traditional IRA
• Roth IRA
• Defined benefit plan
• Cash balance plan
• A regular small-business 401(k)

For a business with employees, a traditional 401(k) or SIMPLE IRA may be more appropriate than a Solo 401(k).

A high-income business owner may also consider a defined benefit or cash balance plan, although these arrangements generally involve more complex administration and funding requirements.

A Retirement Planning Checklist for Self-Employed Workers

Before opening a retirement account, review the following points.

Business eligibility

• Does your business have employees?
• Are any employees eligible under retirement plan rules?
• Is your spouse the only employee besides you?
• Do you operate multiple businesses?
• Could controlled-group rules affect your eligibility?

Contribution planning

• What is your estimated net business income?
• Have you already contributed to another employer’s 401(k)?
• How much can you realistically contribute?
• Do you want employee deferrals and employer contributions?
• Are catch-up contributions available?

Tax considerations

• Do you prefer traditional or Roth contributions?
• Do you have existing SEP, SIMPLE, or traditional IRA balances?
• Could the pro-rata rule affect a backdoor Roth strategy?
• How will contributions affect your current tax return?

Account features

• Does the provider offer the investments you want?
• Are there annual account or administration fees?
• Are Roth contributions available?
• Does the plan allow loans?
• What reporting requirements apply?

Answering these questions before opening an account can help prevent expensive mistakes later.

Frequently Asked Questions About Solo 401(k) vs. SEP IRA

Is a Solo 401(k) better than a SEP IRA?

Neither plan is universally better. A Solo 401(k) may be more attractive for an eligible owner-only business because it allows both employee and employer contributions. A SEP IRA may be easier to administer and can work for businesses with eligible employees.

What is the 2026 Solo 401(k) contribution limit?

For 2026, the basic employee elective-deferral limit is $24,500. The overall defined contribution limit is generally $72,000, excluding catch-up contributions. Your actual contribution depends on eligible compensation, business earnings, and applicable rules.

What is the 2026 SEP IRA contribution limit?

For 2026, the general maximum is the lesser of 25% of eligible compensation or $72,000. Self-employed individuals must use a special calculation based on adjusted net earnings.

Can I contribute to a SEP IRA and a Solo 401(k) in the same year?

It may be possible in certain circumstances, but contribution limits and employer aggregation rules apply. Employee elective deferrals are generally shared across applicable plans. Consult a tax professional before contributing to both.

Can I have a Solo 401(k) if I have employees?

A Solo 401(k) is generally intended for a business owner with no eligible common-law employees other than a spouse. If you hire employees who meet retirement plan eligibility requirements, you may need to include them in a qualified plan.

Can I use a Solo 401(k) if I am a freelancer?

Yes. Freelancers and independent contractors with eligible self-employment income may establish a Solo 401(k), provided they meet the plan’s eligibility requirements.

Can I use a SEP IRA if I have employees?

Yes. SEP IRAs can cover eligible employees. The employer generally must contribute the same percentage of compensation for all eligible participants.

Does a SEP IRA allow catch-up contributions?

No. A SEP IRA does not provide the separate age-based employee catch-up contribution feature available in many 401(k) plans.

Can I make Roth contributions to a Solo 401(k)?

Yes, if the plan document and provider support Roth elective deferrals. Roth contributions are made with after-tax money, and qualified distributions can be tax-free.

Can a SEP IRA be Roth?

Certain SEP arrangements may permit Roth employer contributions under SECURE 2.0 if the plan supports them and applicable requirements are satisfied. Availability depends on the plan provider and document.

Can I borrow money from a SEP IRA?

Generally, no. SEP IRAs follow IRA rules, and IRA owners cannot borrow from their own IRA accounts. Some Solo 401(k) plans may permit participant loans if the plan document allows them.

Does a Solo 401(k) reduce self-employment taxes?

Generally, traditional retirement contributions do not reduce the net earnings used to calculate self-employment tax in the same way that they may reduce income subject to federal income tax. The exact tax treatment depends on the contribution type and business structure.

Can I open a Solo 401(k) and still contribute to a Roth IRA?

Potentially, yes. Roth IRA eligibility depends on income, filing status, and other IRS rules. Having a Solo 401(k) does not automatically prevent Roth IRA contributions.

When should I open a Solo 401(k) or SEP IRA?

The right timing depends on your business structure, tax year, and contribution type. Solo 401(k) deferral elections can have specific timing requirements, while SEP IRA contributions generally have more flexibility around the tax-filing deadline. Check the current IRS rules before establishing a plan.

Conclusion: Choose the Retirement Plan That Fits Your Business

Self-employed workers need a retirement strategy that works with their income and business structure.

A Solo 401(k) offers the opportunity to contribute in both employee and employer capacities. For eligible owner-only businesses, this structure can provide substantial retirement savings opportunities and additional features such as Roth deferrals or plan loans, depending on the plan.

A SEP IRA offers a simpler employer-contribution arrangement. It can be useful for freelancers and businesses that want flexible employer contributions without managing employee salary deferrals.

However, the presence of eligible employees can significantly change the cost and suitability of either arrangement.

Before making a decision, compare the 2026 contribution limits, employee eligibility rules, tax treatment, administrative requirements, and your expected business income.

Most importantly, calculate your actual contribution using the IRS rules rather than relying on a headline percentage.

The best retirement plan is not necessarily the one with the highest advertised contribution limit. It is the one you can fund consistently, administer correctly, and maintain as your business grows.

Sources and Further Reading

• IRS – One-Participant 401(k) Plans: https://www.irs.gov/retirement-plans/one-participant-401k-plans
• IRS – 401(k) and Profit-Sharing Plan Contribution Limits: https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-401k-and-profit-sharing-plan-contribution-limits
• IRS – Publication 560, Retirement Plans for Small Business: https://www.irs.gov/publications/p560
• IRS – 2026 Retirement Plan Contribution Limit Announcement: https://www.irs.gov/newsroom/401k-limit-increases-to-24500-for-2026-ira-limit-increases-to-7500
• IRS – Retirement Plan Contributions: https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-contributions