"Solo 401(k)s offer substantial retirement savings potential due to their high contribution limits for business owners without common-law employees. New rules starting in 2026 will require 'high earners' to make catch-up contributions as Roth, impacting solo 401(k) participants receiving W-2 wages. Properly identifying what qualifies as a 'catch-up contribution' can be complex and may not always align with separate elections."  MORE >>