So what? Why are so many people afraid to be audited? The gov is checking your math... as long as you did it right I don't understand what the problem is.
"We'd like you to come in and talk about your tax return"
"Happy to, just give me a letter of immunity; otherwise i'm pleading the fifth"
This works a little under 50% of the time because that's about how many cases of Audit are actually just the IRS fishing. If they have something then they won't ask you to come down, they will tell you you are legally required to show up.
"We require that you come down here"
"are you legally compelling me?"
"Yes, you are legally required to come here"
This is where you take your big-bag of receipts, documents, letters, expense reports and everything else down and lay it on the table.
When they see this they will realize that you've got your shit together and that getting money from you is going to be a headache.
"We think you owe an extra 10k"
"I don't owe any more, these are my documents."
"If we find an error we'll charge you penalties and interest much greater than the 10k"
"Everything is in order, I have no doubt"
: they look at the entire year worth of grocery receipts et al.:
"How about 2k and we make this go away"
at which point you pay the 2k and you get them to go away.
This is how you deal with the IRS; You may think there are laws, procedures, practices, rules etc. But the truth is that they are thugs with guns that get to re-interpret the rules: everything is ambiguous and everyone is subject to being screwed by these guys.
But they have to document screwing you; so know the rules, know that there's a guy on the other end of the table who doesn't want to go through a bag full of receipts and then negotiate.