As a business owner, planning for your own retirement while supporting your employees’ financial future can play an important role in your broader financial strategy. Two common retirement plan options—SEP IRAs and 401(k) plans, including Solo or Individual 401(k)s for self-employed business owners—offer valuable tax advantages, but they differ in how contributions work, who is eligible, and the level of administrative responsibility involved.
Understanding the differences between these plans can help you choose an option that aligns with your business goals, workforce needs, and long-term retirement strategy.
SEP IRA Basics
A SEP (Simplified Employee Pension) IRA is often used by self-employed individuals and small business owners who want a relatively simple retirement plan with fewer administrative requirements.
Under a SEP IRA:
- Only the employer contributes
- Contributions are made into each eligible employee’s SEP IRA
- Employees cannot make salary deferral contributions
For businesses with few employees—or owners looking for flexibility in annual contribution amounts—a SEP IRA may be an appealing option.
401(k) Plan Basics
A 401(k) plan allows both employee salary deferrals and employer contributions, offering more flexibility than a SEP IRA.
Employees can choose to contribute a portion of their pay, while employers may also:
- Match employee contributions
- Make profit-sharing contributions
- Offer Roth contribution options, depending on the plan
This structure often makes 401(k) plans attractive for businesses focused on employee recruitment, retention, and long-term benefits planning.
Solo or Individual 401(k)
Business owners without employees may also consider a Solo 401(k), sometimes called an Individual 401(k).
A Solo 401(k) is designed for self-employed individuals and business owners with no employees other than a spouse. These plans can offer several advantages, including:
- The ability to make both employee and employer contributions
- Higher potential contribution flexibility at lower income levels compared to some SEP IRAs
- Roth contribution options in many plans
- Loan features, depending on the plan
Because Solo 401(k)s allow owners to contribute in two capacities—employee and employer—they can sometimes allow for larger total retirement contributions than a SEP IRA, particularly for business owners with moderate income levels.
However, Solo 401(k)s may involve additional administrative responsibilities once plan assets exceed certain IRS thresholds.
Key Differences Between SEP IRAs and 401(k) Plans
Below is a closer look at how contributions, eligibility, vesting, and plan features differ between the two retirement plan options.
Contributions
SEP IRA Contribution Limits (2026)
With a SEP IRA:
- Only employers contribute
- Contribution amounts can vary from year to year
- Employers generally must contribute the same percentage of compensation for all eligible employees
For 2026, employer contributions are generally limited to the lesser of:
- 25% of eligible compensation, or
- $72,000
Contribution calculations for self-employed individuals may differ slightly due to IRS adjustment formulas.
401(k) Contribution Limits (2026)
With a 401(k):
- Both employees and employers may contribute
- Employees can make pretax and, in some plans, Roth contributions
Employee Contribution Limits
- $24,500 elective deferral limit
- Additional $8,000 catch-up contribution for individuals age 50 and older
This means eligible individuals age 50+ can generally contribute up to $32,500 in 2026.
Under SECURE 2.0, eligible participants ages 60–63 may qualify for a higher catch-up contribution limit of $11,250 if their employer plan permits it.
Total Contribution Limits
In addition to employee salary deferrals, employers may also contribute through matching or profit-sharing contributions.
The combined annual employee and employer contribution limit is generally:
- Up to $72,000 in 2026
- Catch-up contributions are allowed in addition to this limit for eligible participants
This flexibility can be especially valuable for self-employed individuals using a Solo or Individual 401(k), since these plans allow business owners to contribute as both the employee and employer.
Eligibility Requirements
SEP IRA Eligibility
Generally, employees must be included in a SEP IRA if they:
- Are at least age 21
- Worked for the employer in at least 3 of the previous 5 years
- Earned at least $800 in compensation during 2026
Employers may choose less restrictive eligibility requirements if desired.
401(k) Eligibility
401(k) plans offer employers more flexibility when setting eligibility rules, subject to federal requirements.
Many plans require employees to:
- Be at least age 21
- Complete a service requirement, often up to one year and 1,000 hours worked
Long-term part-time employee rules under federal law may also require eligible part-time employees to be allowed to participate.
Because eligibility rules can vary by plan design, reviewing the details of your specific plan is important.
Vesting Rules
SEP IRA Vesting
All SEP IRA employer contributions are immediately 100% vested.
This means employees fully own all employer contributions as soon as they are made.
401(k) Vesting
Employee salary deferrals are always fully vested immediately.
However, employer matching or profit-sharing contributions may follow a vesting schedule, which can help support employee retention strategies.
Loan Availability
SEP IRA Loans
Loans are not permitted from SEP IRAs.
Withdrawals taken before age 59½ may generally be subject to income taxes and an additional 10% early withdrawal penalty unless an exception applies.
401(k) Loans
Many 401(k) plans allow participant loans.
Generally, participants may borrow up to:
- 50% of their vested account balance
- A maximum of $50,000
Loans typically must be repaid with interest within a specified period.
For some employees, loan access may provide additional flexibility during temporary financial challenges.
Administrative Complexity
One important difference between SEP IRAs and 401(k) plans is administrative responsibility.
SEP IRAs are often easier and less expensive to administer because they generally involve:
- Fewer filing requirements
- Simpler setup and maintenance
- No annual nondiscrimination testing
401(k) plans often involve more administrative oversight, including:
- Annual plan testing
- Additional compliance requirements
- Ongoing plan administration and reporting
However, the additional flexibility and employee benefit features may outweigh the added complexity for some businesses.
Which Retirement Plan May Be Right for Your Business?
The right retirement plan depends on factors such as:
- The size of your business
- Whether you have employees
- Your retirement savings goals
- Your budget for employer contributions
- The level of administrative complexity you are comfortable managing
A SEP IRA may make sense if you:
- Are self-employed, operate a solo business, or have few employees
- Prefer a simpler retirement plan structure
- Want flexibility in annual employer contributions
- Want lower administrative costs
A 401(k) plan may make sense if you:
- Want employees to contribute directly
- Want to offer a competitive employee benefit
- Want features such as Roth contributions, loans, or vesting schedules
- Are seeking higher long-term contribution potential
- Operate a solo business and want greater contribution flexibility
- Want the ability to make both employee and employer contributions
Both retirement plan options offer valuable tax advantages, but they are designed to serve different business and retirement planning needs.
Bringing Your Retirement Strategy Together
Choosing a retirement plan is an important financial decision that can affect both your business and your long-term financial goals. Understanding contribution limits, eligibility rules, administrative responsibilities, and employee benefit considerations can help you make a more informed choice.
At Navalign Wealth Partners, we help business owners evaluate retirement plan options and build strategies that align with their goals, workforce needs, and long-term financial plans. Whether you’re considering a SEP IRA, a 401(k), or another retirement solution, our team is here to help guide you through the decision-making process.