Solo 401(k) 2026 Limits, in Plain English

Every fall the IRS announces next year's retirement contribution limits. For 2026 the headline numbers are: $23,500 elective deferral, $7,500 catch-up at 50, $11,250 super catch-up at 60-63, and $70,000 combined cap. Here's what each one actually does inside a Solo 401(k).

Employee elective deferral: $23,500

This is your slice, money you redirect from your paycheck or net SE earnings into the plan. The cap is per person, not per plan, so a day-job 401(k) and a Solo 401(k) share the same $23,500 ceiling. Roth or Traditional, your choice. Inside a Solo 401(k) you wear two hats: as employee you make this deferral, as employer you add profit sharing on top.

Employer profit sharing: 25% / 20%

S-Corp owners contribute 25% of W-2 wages. Sole proprietors and single-member LLCs contribute 25% of net SE earnings, which works out to about 20% of Schedule C profit thanks to the deduction-of-the-contribution circular math. The IRS publishes a worksheet but the calculator does it for you.

Combined cap: $70,000

Employee + employer can't exceed $70,000 in 2026. Push more in and the IRS calls it an excess contribution and bills you 6% per year until you fix it. The cap rises with inflation each fall.

Catch-up at 50: $7,500

Once you turn 50 in 2026 you open another $7,500 of employee deferral room. Combined ceiling moves from $70,000 to $77,500. Catch-up only adds to the employee deferral side; it doesn't change the employer math.

Super catch-up at 60-63: $11,250

SECURE 2.0 created this special tier. Between 60 and 63 your catch-up jumps from $7,500 to $11,250, a $3,750 bonus. Combined ceiling moves to $81,250. At 64 you drop back to $7,500 and the ceiling falls to $77,500 again.

Compensation cap: $350,000

Ignored at most income levels. But for high-earning S-Corp owners and consultants making over $350k, the IRS only counts the first $350k when calculating the 25% employer share. So the employer share caps at $87,500 even if your salary is $500k. Combined cap $70,000 trims it back to $46,500 effective.

Catch-up Roth rule for high earners

SECURE 2.0 says people earning over $145k W-2 (indexed) must take their catch-up as Roth. The IRS delayed enforcement until 2026 to give plans time. Check with your provider before relying on a Traditional catch-up if you're a high earner.

What the calculator does with this

Punch your income, age, and entity type. The calculator runs the full waterfall, employee deferral cap, catch-up tier, employer share, combined ceiling, % of cap consumed, and spits out one clean total. Used the calculator? Try a few what-ifs: What if I switched from sole prop to S-Corp at $200k? What if I bumped salary by $20k to open more employer share? The math runs in real time.

Glossary cross-links

For deeper definitions: elective deferral, profit sharing, catch-up, SECURE Act 2.0, compensation cap.