SEP-IRA vs Solo 401(k) 2025
Complete Contribution Limits & Comparison for Self-Employed
๐Table of Contents
SEP-IRA vs Solo 401(k): Quick Comparison
If you're self-employed, a freelancer, or run a one-person business, choosing between a SEP-IRA and Solo 401(k) is one of the most important retirement planning decisions you'll make. Both allow massive tax-deferred contributions (up to $69,000 in 2025), but they work very differently.
๐ก Bottom Line Up Front
Solo 401(k) is better for most self-employed individuals earning $60k+ because it allows higher contributions at lower income levels (thanks to the $23,500 employee deferral). SEP-IRA is simpler and better if you want minimal paperwork and plan to contribute under $20k/year. Both max out at $69,000 annually for those earning $276k+.
| Feature | SEP-IRA | Solo 401(k) |
|---|---|---|
| 2025 Max Contribution | $69,000 (25% of compensation) | $69,000 ($23.5k employee + profit-sharing) |
| Age 50+ Catch-Up | โ Not available | โ +$7,500 ($77,500 total) |
| Contribution Formula | 25% of net SE income only | $23.5k + 25% of compensation |
| Roth Option | โ No Roth option | โ Roth 401(k) available |
| Loan Option | โ Cannot borrow | โ Borrow up to $50k |
| Setup Complexity | Very simple (5 min) | Moderate (15 min) |
| Annual Filings | None (unless $250k+ assets) | Form 5500-EZ if $250k+ assets |
| Contribution Deadline | Tax filing deadline (Apr 15 + extensions) | Employee: Dec 31 | Employer: Apr 15 |
| Setup Cost | $0 (free at Vanguard, Fidelity, Schwab) | $0-50 (free at most brokerages) |
| Best For | Simple setup, contributions under $20k/year | Max contributions, Roth option, income $60k+ |
2025 Contribution Limits Explained
SEP-IRA Contribution Limits (2025)
SEP-IRA contributions are calculated as 25% of your net self-employment income (after deducting half of your self-employment tax). The maximum contribution is $69,000 in 2025.
SEP-IRA Calculation Example: $100,000 Net Profit
โข Net self-employment income: $100,000
โข Minus 1/2 SE tax: $100k ร 92.35% ร 15.3% รท 2 = -$7,065
โข Adjusted net income: $92,935
โข SEP-IRA contribution (25%): $92,935 ร 0.25 = $23,234
Note: The actual calculation uses 20% of gross SE income as a shortcut (20% ร $100k = $20k), but the IRS formula is 25% of net after SE tax adjustment.
Solo 401(k) Contribution Limits (2025)
Solo 401(k) has TWO contribution types that stack:
- Employee deferrals: Up to $23,500 (100% of first $23.5k earned) โ this is the game-changer
- Employer profit-sharing: Up to 25% of compensation (same as SEP-IRA)
- Combined maximum: $69,000 in 2025
- Age 50+ catch-up: Additional $7,500 employee deferrals (total $77,500)
Solo 401(k) Calculation Example: $100,000 Net Profit
โข Net self-employment income: $100,000
โข Employee deferral: $23,500 (max for 2025)
โข Adjusted net for employer: $100k - $7,065 (1/2 SE tax) - $23,500 (employee contrib) = $69,435
โข Employer profit-sharing (25%): $69,435 ร 0.25 = $17,359
โข Total Solo 401(k) contribution: $23,500 + $17,359 = $40,859
Solo 401(k) allows $17,625 MORE than SEP-IRA on the same income!
Side-by-Side at Different Income Levels
| Net Profit | SEP-IRA Max | Solo 401(k) Max | Advantage |
|---|---|---|---|
| $40,000 | ~$8,000 | ~$27,100 | Solo 401(k) +$19,100 |
| $60,000 | ~$12,000 | ~$32,400 | Solo 401(k) +$20,400 |
| $80,000 | ~$16,000 | ~$37,700 | Solo 401(k) +$21,700 |
| $100,000 | ~$20,000 | ~$40,859 | Solo 401(k) +$20,859 |
| $150,000 | ~$30,000 | ~$51,100 | Solo 401(k) +$21,100 |
| $200,000 | ~$40,000 | ~$61,000 | Solo 401(k) +$21,000 |
| $276,000+ | $69,000 (max) | $69,000 (max) | Equal at max |
โ ๏ธ Key Insight
Solo 401(k) allows $20,000+ more in contributions at typical freelancer income levels ($60k-150k) thanks to the $23,500 employee deferral. They only equalize at $276k+ income when both hit the $69k max.
SEP-IRA: Simple, Flexible Retirement Plan
SEP-IRA stands for Simplified Employee Pension Individual Retirement Account. It's the easiest self-employed retirement plan to set up and maintain.
How SEP-IRA Works
- Contributions: You (as the employer) contribute up to 25% of your net self-employment income
- Tax treatment: Contributions are tax-deductible, reduce your taxable income immediately
- Withdrawals: Tax-deferred growth until retirement; withdrawals taxed as ordinary income
- Required distributions: Must start taking RMDs at age 73 (as of 2025)
- Early withdrawal penalty: 10% penalty + income tax if withdrawn before age 59ยฝ (with exceptions)
SEP-IRA Advantages
โ Pros
- Extremely simple setup: 5-minute online application, one-page form
- No annual filings: No Form 5500 required unless assets exceed $250k
- Flexible contributions: Contribute different amounts each year (0% to 25%)
- Late contribution deadline: Contribute until tax filing deadline (April 15 + extensions)
- Free setup: $0 at Vanguard, Fidelity, Schwab, E*TRADE
- Scales with employees: If you hire later, SEP-IRA contributions are same % for everyone
โ ๏ธCons
- Lower contributions at typical income: Only 25% vs Solo 401(k)'s $23.5k + 25%
- No Roth option: All contributions are pre-tax (can't do Roth SEP-IRA)
- No catch-up contributions: Age 50+ get no extra contribution room
- No loan provision: Cannot borrow from your SEP-IRA
- Must contribute same % for employees: If you contribute 20% for yourself, must do 20% for employees
Who Should Choose SEP-IRA?
SEP-IRA is best for:
- Simplicity seekers: You value minimal paperwork over maximum contributions
- Variable income: Your income fluctuates wildly year-to-year (easy to adjust contributions)
- Lower contribution goals: You plan to save under $20k/year for retirement
- High earners ($250k+): Both plans max at $69k, so SEP-IRA's simplicity wins
- Future employees possible: You might hire W-2 employees (SEP-IRA scales better than Solo 401k)
- Last-minute savers: You often wait until tax time to decide retirement contributions
Solo 401(k): Maximum Contribution Power
Solo 401(k) (also called Individual 401(k) or One-Participant 401(k)) is a traditional 401(k) plan designed for self-employed individuals with no employees (except a spouse).
How Solo 401(k) Works
You wear TWO hats with a Solo 401(k):
- As the employee: Defer up to $23,500 of your income (like a W-2 employee's 401k contributions)
- As the employer: Contribute up to 25% of your compensation as "profit-sharing"
- Combined limit: Total contributions capped at $69,000 (or $77,500 if age 50+)
Real Example: $90,000 Net Profit, Age 52
Employee Deferrals:
โข Base limit: $23,500
โข Age 50+ catch-up: +$7,500
โข Total employee: $31,000
Employer Profit-Sharing:
โข Net profit: $90,000
โข Minus 1/2 SE tax: -$6,359
โข Minus employee deferrals: -$31,000
โข Adjusted compensation: $52,641
โข Employer contribution (25%): $13,160
Total 2025 Contribution: $31,000 + $13,160 = $44,160
(Compare to SEP-IRA: ~$18,000 on same income โ that's $26,160 less!)
Solo 401(k) Unique Features
๐ฏ Roth 401(k) Option
You can designate all or part of your employee deferrals ($23,500) as Roth contributions. These are after-tax now but grow tax-free foreverโno taxes on withdrawals in retirement. SEP-IRA doesn't offer this.
๐ฐ Loan Provision
You can borrow up to $50,000 or 50% of your account balance (whichever is less) and pay it back with interest to yourself. Useful for emergencies without the 10% early withdrawal penalty.
๐ Mega Backdoor Roth (Advanced)
If your Solo 401(k) plan document allows it, you can make after-tax contributions beyond the $23,500 limit (up to the $69k total) and immediately convert them to Roth. This is the "mega backdoor Roth" strategy for high earners.
Solo 401(k) Advantages & Disadvantages
โ Pros
- Much higher contributions: $20k+ more at typical income levels vs SEP-IRA
- $23,500 employee deferrals: Contribute from first dollar earned (not just 25%)
- Roth option: Tax-free retirement income via Roth 401(k) contributions
- Age 50+ catch-up: Extra $7,500/year (total $77,500 vs SEP's $69k)
- Loan access: Borrow up to $50k from your own plan
- Free setup: $0 at Fidelity, Schwab, E*TRADE, Vanguard
โ ๏ธCons
- Slightly more setup: 15-minute application vs SEP's 5 minutes
- Form 5500-EZ filing: Required annually if assets exceed $250k
- December 31 deadline: Employee deferrals must be made by Dec 31 (not Apr 15)
- Plan adoption agreement: Need to sign plan documents (still free)
- Employee complications: If you hire non-spouse employees, must switch to regular 401(k)
Who Should Choose Solo 401(k)?
Solo 401(k) is best for:
- Maximum savers: You want to shelter as much income as possible from taxes
- Consistent income $60k+: High enough to benefit from the $23.5k employee deferral
- Age 50+: The $7,500 catch-up is a huge advantage ($77.5k total)
- Roth preference: You want tax-free retirement income (Roth 401k option)
- True solopreneurs: You're confident you won't hire employees (hiring complicates Solo 401k)
- December planners: You can decide contributions by end of year (not waiting until April)
Real-World Contribution Scenarios
๐ป Freelance Developer: $75k Net Profit, Age 35
SEP-IRA Contribution
โข 25% of adjusted income
โข ~$15,000 contribution
โข Tax savings (24% bracket): $3,600
โข Remaining income: $60,000
Solo 401(k) Contribution
โข Employee: $23,500
โข Employer: ~$12,875
โข Total: $36,375
โข Tax savings (24% bracket): $8,730
Saves $21,375 MORE for retirement!
Best choice: Solo 401(k) โ allows nearly 2.5x the contribution
โ๏ธ Freelance Writer: $35k Net Profit, Age 28
SEP-IRA Contribution
โข 25% of adjusted income
โข ~$7,000 contribution
โข Simple setup, late deadline (April 15)
Solo 401(k) Contribution
โข Employee: up to $23,500 (could contribute full $35k!)
โข Practical max: ~$20,000 (leave $15k to live on)
โข More admin, Dec 31 deadline
Best choice: SEP-IRA โ at lower income, simplicity matters more. Can save $7k easily by April deadline.
๐ธ Photographer: $120k Net Profit, Age 54
SEP-IRA Contribution
โข 25% of adjusted income
โข ~$24,000 contribution
โข No catch-up available
โข Max: $24,000
Solo 401(k) Contribution
โข Employee: $23,500
โข Age 50+ catch-up: $7,500
โข Employer: ~$19,000
Total: $50,000
Saves $26,000 MORE!
Best choice: Solo 401(k) โ catch-up contributions alone make it a no-brainer for age 50+
๐ผ Consultant: $300k Net Profit, Age 42
SEP-IRA Contribution
โข 25% of adjusted income
โข Max: $69,000
โข Simpler setup/maintenance
โข No annual filings (under $250k assets)
Solo 401(k) Contribution
โข Employee: $23,500
โข Employer: $45,500
โข Max: $69,000 (same)
โข Roth option available
Best choice: Toss-up โ both max at $69k. Choose SEP-IRA for simplicity or Solo 401(k) if you want Roth option.
Which Plan Should You Choose?
Decision Flowchart
Are you age 50 or older?
โ YES: Choose Solo 401(k) for $7,500 catch-up ($77,500 total)
โ NO: Continue to question 2
Is your net profit $60,000 or more?
โ YES: Choose Solo 401(k) for $20k+ extra contribution room
โ NO: Continue to question 3
Do you want Roth (tax-free) retirement income?
โ YES: Choose Solo 401(k) (only plan with Roth option)
โ NO: Continue to question 4
Might you hire employees (non-spouse) in the next 3-5 years?
โ YES: Choose SEP-IRA (scales better with employees)
โ NO: Continue to question 5
Do you value extreme simplicity over maximum contributions?
โ YES: Choose SEP-IRA (5-min setup, no annual filings)
โ NO: Choose Solo 401(k) (maximum contribution power)
Quick Reference Guide
Choose SEP-IRA If:
- โ Net profit under $60k
- โ You want the simplest possible setup
- โ You plan to contribute under $20k/year
- โ Your income fluctuates wildly (easy to adjust contributions)
- โ You often decide contributions at tax time (April deadline)
- โ You might hire employees soon
- โ Net profit $276k+ (both plans max at $69k, so SEP is simpler)
Choose Solo 401(k) If:
- โ Net profit $60k or more
- โ You want maximum tax-deferred contributions
- โ You're age 50+ (catch-up contributions)
- โ You want Roth option (tax-free retirement)
- โ You value loan access (borrow up to $50k)
- โ You're a true solopreneur (no plans to hire)
- โ You can commit to contributions by December 31
๐ก Can You Switch Plans Later?
Yes! You can have both a SEP-IRA and Solo 401(k) open, but you can't maximize both in the same year (they share the $69k limit). Many people start with SEP-IRA for simplicity, then switch to Solo 401(k) when their income crosses $60k. You can rollover SEP-IRA funds into a Solo 401(k) if desired.
Setup Process & Costs
Setting Up a SEP-IRA (5 Minutes)
Choose a Brokerage
Vanguard, Fidelity, Schwab, E*TRADE all offer free SEP-IRA setup. Pick one with low expense ratio index funds.
Complete Online Application
Provide SSN or EIN, business name, choose investments. Takes 5 minutes.
Fund Your Account
Transfer money from business checking. Contributions can be made anytime until your tax filing deadline (April 15 or Oct 15 with extension).
Deduct on Your Tax Return
Report SEP-IRA contributions on Schedule 1 (Form 1040), line 16. Reduces taxable income dollar-for-dollar.
Total setup cost: $0 | Annual maintenance: $0 (no filings unless assets exceed $250k)
Setting Up a Solo 401(k) (15 Minutes)
Choose a Provider
Fidelity, Schwab, E*TRADE, Vanguard offer free Solo 401(k) plans. Check if they offer Roth option if you want it.
Complete Plan Adoption Agreement
Online application (~10-15 minutes). You'll sign a plan document establishing the Solo 401(k).
Get an EIN (If Needed)
The Solo 401(k) plan needs its own EIN (separate from your business EIN). Free from IRS, takes 5 minutes online.
Make Contributions
โข Employee deferrals: Must be made by Dec 31 of tax year
โข Employer profit-sharing: Can be made until tax filing deadline (April 15 or extension)
File Form 5500-EZ (If Required)
Only if plan assets exceed $250,000. Due by July 31 (or Oct 15 with extension). Simple one-page form.
Total setup cost: $0-50 | Annual maintenance: $0 (until $250k+ assets, then $50-200 for 5500-EZ filing)
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Anand Godar
Financial engineer and founder of QuantCurb. Former fintech data scientist building institutional-grade calculators for everyday wealth decisions.
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