I have the same question about the accounting / bookkeeping aspect of the solo 401k contribution.  What is the best way to set up quickbooks (online) to account for the solo 401k contributions.  I am a sole proprietorship LLC (not an S corp) like the couple with the prior question.  Therefore it's going to go on my personal taxes, but what I'm trying to figure out is the best way to bookkeep for contributions on quickbooks online (i.e. what account to pull from, or create a new one, etc.).  Any guidance would be much appreciated from someone who has done this before.  Thanks