This is exactly why so many people ask to have an attorney present when they are going through this process. It is not simply to drag out this questioning with the IRS longer than it has to go. Rather, it is about making sure that there is a clear record of everything that was said. It is about protecting oneself from a possible onslaught by the IRS in the long run.
Making a recording of an interview with the IRS is perfectly legal. In order to do so though, one needs to make that request in writing to the IRS at least ten days in advance of their scheduled interview. That is the only way that permission to do so can be granted.
If you are to record your interview, you must bring your own audio equipment along. The IRS is allowed to do the same but would also have to provide you with ten days advanced notice that this is what they planned to do. If the IRS decides to record your interview, they will bring their own audio equipment as well.
There is a big debate about the idea of recording an interview with an auditor. While some say that this is the only way to guarantee that the record is written down in stone, others say that it sends the wrong message to the auditor who may get the impression that you are trying to cover something up. You want a healthy relationship with the auditor, and it should be a relationship in which the two of you are able to trust one another. If that isn’t happening, then there are already problems going forward.
It might be best to lay off the request to record the interview for the time being. You do not want the IRS to get the notion that you are attempting to conceal something from them. They will find out if you are trying to hide something anyway. It is best to avoid even the suspicion that this is what you might be doing.
Just because you have the legal right to do something does not mean that this is the route that you ought to take. There are other choices that can be made in these situations. Perhaps you should take a look into those and see if just going to the interview without a recording might be the better option for your circumstances. You never know how things might turn out.