Has the IRS has contacted your business associates or other third parties? Normally, if you are subject to an audit, the IRS must contact you to let you know that they will be doing checking with others about you. They must give you a list of who they contacted. See below for the IRS info about them contacting your bank, employers, employees, etc…
The IRS must give you reasonable notice before contacting other persons about your tax matters. You must be given reasonable notice in advance that, in examining or collecting your tax liability, the IRS may contact third parties such as your neighbors, banks, employers, or employees. The IRS must also give you notice of specific contacts by providing you with a record of persons contacted on both a periodic basis and upon your request.
However, and this is a big one, they will not tell you about these third-party contacts if you are being investigated criminally. That would be really bad. You need the services of a good tax professional and an attorney. As an EA, I would work under the auspices of attorney-client privilege. Essentially, the attorney hires me to perform my services and this enables attorney-client privilege for my services.
Hopefully, this is not the case for you. Another reason that the IRS would not notify you about third-party contacts is if they thought you would take actions that would make it difficult for them to collect any monies owed. The IRS can also avoid notifying you if they have reason to believe that you would take action against anyone who provided information about you.
Finally you can authorize the IRS to contact certain parties, but I would not do this without the advice of a tax professional. See the IRS language about these clauses from Pub 556
This provision does not apply:
- To any pending criminal investigation,
- When providing notice would jeopardize collection of any tax liability,
- Where providing notice may result in reprisal against any person, or
- When you authorized the contact.