Solo 401(k)
A 401(k) for a business owner with no employees other than a spouse, where you contribute both as the employee and as the employer.
As the employee, you can defer salary up to the regular 401(k) limit. As the employer, you can add up to 25% of compensation, about 20% of net profit for a sole proprietor. Both parts together are capped by the overall yearly limit for defined contribution plans.
Many providers offer a Roth option for the employee part. Once the plan holds $250,000 or more at year end, you generally file Form 5500-EZ.
Example
A $14,870 employer share plus a $24,500 employee deferral is $39,370 for the year.