Every day I talk to small-business owners who are hustling, grinding, freelancing, consulting, side-gigging, or somehow doing five jobs at once—and they want to know one thing:
"Where do I put my retirement money so Future Me doesn't hate Present Me?"
Two of the most common tools on the table are the Solo 401(k) and the SEP IRA. They're both legitimate, IRS-approved retirement accounts. They're both simple. They're both powerful. They're both great options, depending on your situation.
But when you zoom out and actually look at the numbers—not the marketing blurbs—you notice something interesting:
One of them quietly laps the other almost every single time.
And it's not even close.
Let's break it down in plain English, with real math and zero jargon. (Or mild jargon, but I promise to translate.)
Two Accounts Walk Into a Bar…
SEP IRA:
The SEP is the minimalist cousin of retirement plans. It shows up with flip-flops, orders water, and says, "Let's keep this easy."
A SEP gives you:
- Employer contributions only
- Up to 25% of W-2 (or ~20% of net self-employment income)
- No employee deferrals
- No Roth contributions (99% of the time)
- No catch-up contributions
- No bells, no whistles, no confetti cannons
Solo 401(k):
The Solo 401(k) shows up in a tailored jacket, orders an espresso, and says, "Actually, we're going to do both."
A Solo 401(k) gives you:
- Employee deferrals up to $23,000 (2025)
- Employer contributions (same formula as SEP)
- Roth option
- Catch-up contributions if you're 50+
- Ability to accept rollovers
- More total contribution space at lower incomes
Why Solo 401(k) Usually Wins
Let's keep this simple:
**The Solo 401(k) has two engines.
The SEP has one.**
Engine #1: Employee Deferral
Engine #2: Employer Contribution
The SEP only gives you engine #2.
This means that for any small business owner making, say, $20,000–$200,000, the Solo 401(k) usually creates much larger contribution room—especially at the lower end of that range, where employer-only formulas hit a wall fast.
Let's look at real numbers, not "marketing math."
Example Time: The "Quietly Brutal" Comparison
Let's say you're a one-person shop and you earn $80,000 in net self-employment income (or W-2 if you're an S-Corp owner).
Here are your options:
SEP IRA Maximum
SEP contribution ≈ 20% of $80,000
≈ $16,000
That's it. That's the whole plan.
Solo 401(k) Maximum
Employee deferral: $23,500
Employer contribution: ~$16,000
Total: $39,000
Identical income.
Double the contribution room.
No tricks. Just IRS math.
This is why so many solo owners feel like the Solo 401(k) is a cheat code. Because if you can contribute $39K instead of $16K… well, that's not exactly a small difference.
"But Dan, what about higher incomes?"
Good question.
If you're earning $300K, $400K, $500K+? (Did someone say Defined Benefit Plan? Ok, ok, I'll save that for another day. Be patient it's coming soon!)
Back to regularly scheduled programming.
The gap starts to shrink because you hit the cap quicker on both plans.
But let's be honest—most freelancers, consultants, gig-economy pros, and self-employed owners are not making $800,000 a year. They're making between $40K and $200K, and that's where the Solo 401(k) absolutely dominates.
The Real Killer Feature: Roth
This part always surprises people.
Most SEP IRAs do not allow Roth contributions.
Period. End of story.
A Solo 401(k), on the other hand?
- Roth employee deferrals
- Pre-tax employee deferrals
- Roth or pre-tax employer contributions (depending on custodian)
- And the ability to split contributions however you want
Now, everyone's tax situation is different. I'm not giving advice. I'm just saying: flexibility is usually better than inflexibility.
Catch-Up Contributions: Another Boost
If you're 50 or older (and blessed with AARP coupons):
- SEP IRA catch-up contributions: $0
- Solo 401(k) catch-up deferral: $7,500
If you're trying to turbo-charge retirement savings in your 50s, this is a big deal.
So When Does the SEP Actually Win?
There are scenarios where the SEP is the right tool.
1. You Have Employees
Once you hire people, the Solo 401(k) exits stage left.
The SEP is much easier to manage because:
- Contributions must be proportional for all eligible employees
- There's no testing
- No employee deferrals to manage
2. You Refuse to Touch Paperwork
A Solo 401(k) requires:
- A plan document
- Amendments over the years
- IRS Form 5500-EZ once assets exceed $250,000
- Slightly more administrative attention
- A one-page form
- Opening an account
If your philosophy is "I want zero paperwork," then yes, the SEP is your soulmate. I hope you live happily ever after.
3. You Don't Care About Roth
Some people truly don't care.
Some don't want Roth.
Some already max Roth IRAs.
Some just want employer contributions.
Fair enough.
But If You're a One-Person Shop?
If you:
- Have no employees
- Are okay with basic paperwork
- Want maximum savings flexibility
- Want Roth options
- Want catch-up contributions
- Want more control
It's not an opinion.
It's not a vibe.
It's not "Dan's hot take of the week."
It's just the IRS contribution formula doing its thing.
The Solo 401(k) Is Not Perfect, But It's Powerful
To be fair:
- You do have to maintain a plan document
- You may need to file a 5500-EZ after $250K in assets
- Some custodians don't support Roth employer contributions
- Some don't support rollovers
- You need to track employee vs employer money correctly
Think of it like a sports car that requires oil changes.
Worth it.
The SEP IRA Is Not "Bad"
The SEP IRA is:
- Easy
- Fast
- Clean
- Simple
- Low-maintenance
- Great for businesses with employees
- Perfect for people who just want employer contributions
But if you want the version with:
- More power
- Roth flexibility
- Higher limits at modest income
- Catch-up contributions
- Two contribution engines
Final Takeaway (and I'll Keep It Simple)
Here it is, boiled down to a single sentence:
A SEP is great, but a Solo 401(k) is usually better for one-person businesses because you get employee deferrals, Roth options, catch-up contributions, and significantly more contribution space at normal income levels.
Same income.
Different results.
No judgment. Just IRS math.
The information in this article is for educational and general informational purposes only. It is not financial, tax, or investment advice, and I am not acting as your advisor. Retirement rules can be complex, your situation is unique, and laws change frequently. Always consult a qualified tax professional or financial advisor before making any decisions related to your personal finances or retirement accounts.
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