In 2006, Congress merged two of the most popular types of retirement savings plans—the Roth IRA and the Solo 401(k).
The Roth Solo 401(k) possesses the same benefits of the solo 401(k), with the tax benefits of the Roth IRA. The contribution limits are the same as the Solo 401(k), but you can designate your contributions through salary deferral as Roth contributions.
In 2019 you can annually contribute up to $19,000 and up to $25,000 if you’re 50 or over through salary deferral. Plus, you can contribute a profit-sharing portion (0-25%) of your salary. In 2019 the limit from both sources is $56,000 ($62,000 if you are 50 or over).
The Roth Solo 401(k) is available to anyone with a Solo 401(k). It’s a benefit to higher-paid employees and self-employed individuals who may have been excluded from having a Roth IRA because of income limitations.