Solo 401k Contribution Limits 2024. For 2024, the solo 401(k) maximum contribution limit for the elective deferral is $23,000 if you’re age 50 and under. The 401 (k) contribution limit is $23,000.

In 2024, you can contribute $23,000 to the roth portion of your solo 401(k). For those with a 401(k), 403(b), or 457 plan through an employer, your new maximum contribution limit will go up to.