UPDATE TO POST: Timing is Everything!
Updated: Apr 23, 2021
An important note about the Self-Directed Solo 401(k) plan adoption deadline has been added to the bottom of this article, originally posted on 9/16/2020.
Self-Directed Solo 401(k)s are a great way for eligible nonemployer business owners to save on taxes by deferring till retirement. They can also help save for retirement in a self-directed and asset class-diversified way. The timing for adopting this kind of plan matters, however, so that the contribution methods can be fully maximized.
Depending on how the business is taxed, time is running out for 2020.

Contribution types – the difference matters for timing
The Self-Directed Solo 401(k) allows for pretax contributions to be made two different ways: Salary Deferral and Profit-Sharing. Here is the 2020 contribution limit breakdown for each and how they are calculated.
Salary Deferral - With salary deferral, the account holder can contribute:
- 100% of net earnings from self-employment up to a maximum of $19,500.
- Those who are 50 years old or older qualify for the additional catch-up contribution of $6,500, bringing the salary deferral limit to $26,000.
Profit-Sharing - In addition to salary deferral, the account holder can also make a profit-sharing contribution:
- For those set up as an LLC, Partnership, or Sole Proprietor, they can contribute up to 20 percent of their net earnings from self-employment.
- Those set up as C Corporations and S Corporations can contribute up to 25 percent of their salary from self-employment.
Combined Limit -