Any direct or indirect benefit between a plan and a disqualified party can result in a prohibited transaction and void the IRA, and there are many ways the IRS could find some form of benefit in such a joint venture.

What kind of jobs focus on selling to people and would benefit me in real estate also?

I like investing in commercial syndications with experienced sponsors for passive cash flow, tax benefits, and appreciation.  

Write offs .. get a cpa and learn all the tax codes and potential benefits 

Compared to an IRA, Solo 401k contribution limits are roughly ten times higher.There is no custodial requirement for the 401k.You don't need the additional expense and administration of an LLC to have checkbook control.There is a built in-Roth component whereas IRAs are either traditional or Roth, not both.A spouse can also participate in the same Solo 401k plan.The Solo 401k has additional tax benefits over an IRA when investing into real estate using leverage.You can borrow from a 401k, but not an IRABoth C-Corps and LLCs can adopt a Solo 401k.

Crowdfunding goes even further, completely breaking from traditional mortgage lending and having to rely on banks.Home SearchHome searches haven’t necessarily benefited from new technology much.

This method would not require monthly payments which is a big benefit in managing cash flow over the life of the debt.

The cost of getting a new loan after putting the first loan on is going to eat up most of the benefit of refinancing, for most situations.

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Although my properties have appreciated nicely I have yet to benefit from the appreciations as I have not sold one property yet.