Solo 401(k) Contribution Limits 2026: Both Buckets, One Worked Example
Quick answer
The solo 401(k) contribution limit for 2026 is $72,000 combined: up to $24,500 in employee deferrals plus an employer contribution of up to 25% of compensation. Savers aged 50 and over add an $8,000 catch-up, or $11,250 at ages 60 to 63, lifting the ceiling to $80,000 or $83,250.
Solo 401(k) contribution limits, 2026 vs 2025
| Limit | 2026 | 2025 |
|---|---|---|
| Employee deferral | $24,500 | $23,500 |
| Catch-up contribution, age 50 and over | $8,000 | $7,500 |
| Higher catch-up, ages 60 to 63 | $11,250 | $11,250 |
| Employer contribution | Up to 25% of compensation (about 20% of net self-employment earnings) | Same formula |
| Combined employee + employer cap (section 415(c)) | $72,000 | $70,000 |
| Maximum with age-50 catch-up | $80,000 | $77,500 |
| Maximum at ages 60 to 63 | $83,250 | $81,250 |
| Compensation cap (section 401(a)(17)) | $360,000 | $350,000 |
| Form 5500-EZ filing trigger | $250,000 of plan assets at year end | $250,000 of plan assets at year end |
The solo 401k contribution limits for 2026 are really two limits stacked on top of each other, because a one-participant plan lets you contribute in both of your roles. As the employee, you can defer up to $24,500, the same figure as any workplace plan and covered in detail in 401(k) contribution limits for 2026. As the employer, you can add up to 25% of compensation. The two buckets together cannot exceed $72,000, before catch-ups.
The trap is the employer-side calculation. For the self-employed, compensation is not gross profit: it is net earnings minus half of your self-employment tax minus the contribution itself, which turns the 25% plan rate into roughly 20% of adjusted net profit. Worked through at $80,000 of net self-employment income for 2026: SE tax is about $11,304, half of which ($5,652) comes off, leaving a contribution base of about $74,348. The employer share is 20% of that, roughly $14,870. Add the full $24,500 deferral and the total is about $39,370, comfortably under the $72,000 cap. Run your own numbers against the rate table in IRS Publication 560 chapter 5 before funding, since entity type changes the arithmetic (S corp owners use W-2 salary, not profit).
That $24,500 employee bucket is precisely what a SEP IRA lacks, which is why the solo 401(k) usually shelters more at ordinary income levels; the full comparison is in SEP IRA vs solo 401(k). And because contributions here reduce income tax but not SE tax, the other lever worth knowing is the QBI deduction. The rest of our US reference shelf is at /us/guides.
This is general information for US readers, not personal advice. The figures are the IRS's published limits for 2026 from Notice 2025-67 and Publication 560.
Frequently asked questions
How is the solo 401(k) employer contribution calculated when self-employed?
Not as a flat 25% of profit. Your compensation is net self-employment earnings minus half of your SE tax minus the contribution itself, which collapses the 25% plan rate to about 20% of net profit after the SE-tax deduction. IRS Publication 560 chapter 5 has the exact rate table and worksheet.
Does the catch-up contribution count toward the $72,000 limit?
No. Catch-ups sit on top of the section 415(c) cap. A 55-year-old can reach $80,000 in 2026 ($72,000 plus the $8,000 catch-up), and someone aged 60 to 63 can reach $83,250 with the higher $11,250 catch-up, provided their earned income supports it.
Can my spouse contribute to my solo 401(k)?
If your spouse genuinely works in the business and is paid for it, they can join the same plan with their own full set of limits: their own $24,500 deferral, their own employer share, their own catch-up. A working couple can shelter up to $144,000 in 2026 before catch-ups.
What is the deadline to set up and fund a solo 401(k) for a tax year?
Sole proprietors with no employees can adopt a plan after year end, up to the tax filing deadline without extensions, and still make first-year contributions including deferrals. After the first year, deferrals must be elected by 31 December; employer contributions can wait until the return due date including extensions.
Do Roth solo 401(k) contributions have a separate limit?
No. Pre-tax and designated Roth deferrals share the single $24,500 limit for 2026. The split between them is yours to choose if your plan document offers a Roth account. Employer contributions count only toward the $72,000 combined cap, not the deferral limit.
When do I have to file Form 5500-EZ?
Once the plan holds $250,000 or more in assets at the end of the plan year, and again in the plan's final year regardless of size. It is an information return, not a tax bill, but late filing penalties are steep, so diarise it once your balance approaches the threshold.
Sources
General information, not financial advice. Tax rules and figures can change; check the current position on irs.gov or ssa.gov before acting.