Calculator
Solo 401(k) calculator
Sole proprietor (Schedule C) or S corporation owner paid W-2 wages. Enter deferrals made to another employer’s plan this year, if any.
2026 solo 401(k) maximum$51,087vs $18,587 in a SEP IRA
| Net earnings after half SE tax | $92,935 |
|---|---|
| Employee deferral | $24,500 |
| Employer 20% of net earnings | $18,587 |
| Catch-up (age 50+, or 60–63) | $8,000 |
| Total solo 401(k) | $51,087 |
| 2026 cap incl. catch-up | $80,000 |
A solo 401(k) is for a business with no employees other than the owner and spouse. Deferrals can be Roth; employer contributions can also be designated Roth under SECURE 2.0 if the plan allows.
The link keeps your inputs, so you can save or share this scenario.
How the solo 401(k) calculator works
A one-participant 401(k) covers a business owner with no employees (or the owner and spouse), and the owner contributes in two roles[oneparticipant]:
- As the employee: elective deferrals up to 100% of earned income, capped at $24,500 for 2026, plus the age-50 or age 60–63 catch-up. Deferrals can be pre-tax or Roth.
- As the employer: a nonelective contribution of up to 25% of compensation. For a sole proprietor, compensation is net earnings after half of self-employment tax and after the contribution itself, which works out to 20% of net earnings[secalc][p560].
- The total of both, not counting catch-ups, can't exceed $72,000 in 2026[k401lim].
An S corporation owner uses W-2 wages instead: the employer share is 25% of those wages, and distributions don't count. You reach the $72,000 total at about $252,400 of 2026 Schedule C profit.
Solo 401(k) limits for 2025, 2026 and 2027
| Limit | 2025 | 2026 | 2027 |
|---|---|---|---|
| Employee deferral | $23,500 | $24,500 | $25,500 |
| Employer share, sole proprietor | 20% of net earnings | 20% of net earnings | 20% of net earnings |
| Employer share, S corp | 25% of W-2 pay | 25% of W-2 pay | 25% of W-2 pay |
| Total, under 50 | $70,000 | $72,000 | $75,000 |
| Total, age 50+ | $77,500 | $80,000 | $83,500 |
| Total, turning 60–63 | $81,250 | $83,250 | $86,750 |
| Compensation counted | $350,000 | $360,000 | $375,000 |
The 2026 figures come from Notice 2025-67 and the 2027 figures from Notice 2026-66[n2567][n2667].
| Net profit | Deferral | Employer 20% | Solo 401(k) total | SEP IRA |
|---|---|---|---|---|
| $60,000 | $24,500 | $11,152 | $35,652 | $11,152 |
| $80,000 | $24,500 | $14,870 | $39,370 | $14,870 |
| $100,000 | $24,500 | $18,587 | $43,087 | $18,587 |
| $150,000 | $24,500 | $27,881 | $52,381 | $27,881 |
| $200,000 | $24,500 | $37,177 | $61,677 | $37,177 |
| $250,000 | $24,500 | $47,043 | $71,543 | $47,043 |
Worked examples
Sole proprietor, $100,000 profit, age 52. Half of self-employment tax is $7,064.78, so net earnings are $92,935.23.
- Employee deferral: $24,500.
- Age-50 catch-up: $8,000.
- Employer share: 20% × $92,935.23 = $18,587.05.
- Total: $51,087.05, about $32,500 more than the $18,587.05 a SEP IRA allows on the same profit.
S corporation owner, $100,000 of W-2 wages, age 52: $24,500 deferral + 25% × $100,000 = $25,000 employer + $8,000 catch-up = $57,500.
Rules to know
- One deferral limit per person. If you also defer $15,000 at a day job in 2026, only $9,500 is left for your solo 401(k); the employer share is not affected[k401lim].
- No employees. Hiring an eligible employee other than your spouse ends solo status; the plan then needs testing and coverage like any 401(k)[oneparticipant].
- Form 5500-EZ is generally required once plan assets reach $250,000 at year end[oneparticipant].
- Low profits. With small profits, deferrals plus the employer share can't exceed your net earnings; the Pub 560 worksheet caps the employer share at half of what is left after deferrals[p560].
Common mistakes with solo 401(k) contributions
- Using 25% of profit for the employer share. For a sole proprietor it is 20% of net earnings after half of SE tax.
- Taking a second $24,500 for a side business. Deferrals at every job share one limit.
- Counting the catch-up inside $72,000. It sits on top: $80,000 at 50+, $83,250 at 60–63.
- Ignoring the 2027 change. The deferral limit rises to $25,500 and the total to $75,000; see the 401(k) contribution limit page.
NextProject the balance with the 401(k) calculator, or compare with the employee limits in the SIMPLE IRA and the full 2026 contribution limits table.
Frequently asked questions
How much can I contribute to a solo 401(k) in 2026?
Up to $24,500 as the employee plus an employer share of 20% of net self-employment earnings (25% of W-2 pay for an S corporation), with a combined cap of $72,000. Catch-ups add $8,000 at 50+ or $11,250 at 60–63.
Is a solo 401(k) better than a SEP IRA?
At the same profit a solo 401(k) usually allows more, because the employee deferral comes on top of the employer share: on $100,000 of 2026 profit at age 45 it is $43,087 versus $18,587 in a SEP. A SEP is simpler and has no annual Form 5500-EZ.
Can I have a solo 401(k) if I have a 401(k) at work?
Yes, for self-employment income. Your deferrals at both share one $24,500 limit, but the employer contribution to the solo 401(k) is separate.
What is the solo 401(k) limit for 2027?
$25,500 of employee deferrals and $75,000 in total, plus $8,500 at 50+ or $11,750 at 60–63 (IRS Notice 2026-66).
Sources
- One-participant 401(k) plans
- Publication 560 (2025), Retirement Plans for Small Business (SEP, SIMPLE, and Qualified Plans)
- Retirement topics: 401(k) and profit-sharing plan contribution limits
- Notice 2025-67, 2026 Amounts Relating to Retirement Plans and IRAs
- Notice 2026-66, 2027 Amounts Relating to Retirement Plans and IRAs, as Adjusted for Changes in Cost-of-Living
- Self-employed individuals: Calculating your own retirement plan contribution and deduction