A truly self-directed Solo401k comes with loan provision. This means borrowing from the account is allowed. You can borrow up to $50,000, or 50% of the total account value, whichever is less. The loan is tax and penalty free, as long as you make payments according to the loan policy. Typically, loan will have to be paid back within 5 years and at least on a quarterly basis. The nice thing is that the interest, together with principal, will be paid back to your own retirement account.