Solo 401(k) Calculator

Find the most a self-employed person can put into a Solo 401(k) or SEP IRA in 2026.

Business type	Sole proprietor / single-member LLC
Net self-employment profit	$120,000
Your age at year end	45
Deferrals already made to other 401(k)s this year	$0

Business type

Net self-employment profit

Your age at year end

Deferrals already made to other 401(k)s this year

Maximum 2026 contribution

$46,804

Employee deferral $24,500 + employer profit-sharing $22,304 (20% of net earnings after half of self-employment tax of $16,955). A SEP IRA would allow only the employer part, about $22,304.

Contribution

Employee deferral52%: $24,500
Employer48%: $22,304

About the Solo 401(k) Calculator

A Solo 401(k) lets a business owner with no employees (other than a spouse) contribute twice: as the employee, up to $24,500 in 2026 (plus $8,000 catch-up at 50+, or $11,250 at ages 60–63), and as the employer, up to 25% of W-2 pay, which for sole proprietors works out to 20% of net self-employment earnings after deducting half of self-employment tax. The combined total is capped at $72,000 plus catch-up, using compensation up to $360,000.

A SEP IRA allows only the employer contribution, so a Solo 401(k) usually allows more at lower incomes. Employee deferrals are shared across all 401(k) plans you're in.

The formula

Sole prop employer limit = 20% × (profit − ½ SE tax); total ≤ $72,000 + catch-up

2026 limits (IRS)

Limit	Amount
Employee deferral	$24,500
Catch-up, age 50+	$8,000
Catch-up, ages 60–63	$11,250
Total annual additions (415(c))	$72,000
Compensation limit	$360,000

Worked example

Example: Maximum 2026 contribution = $56,663

Inputs: Business type: Sole proprietor / single-member LLC; Net self-employment profit: $130,000; Your age at year end: 50; Deferrals already made to other 401(k)s this year: $0.
Formula: Sole prop employer limit = 20% × (profit − ½ SE tax); total ≤ $72,000 + catch-up
Result: Maximum 2026 contribution = $56,663

Questions people ask

Roth or traditional?

Solo 401(k) deferrals can be Roth if the plan allows; SEP IRAs now may allow Roth too under SECURE 2.0.

When is the deadline?

Employer contributions can be made up to the tax filing deadline including extensions.

Sources

The rules and rates this calculator uses come from the official pages below. Its results are estimates, not an official determination, and rules change, so check the latest figures there before you act on them.