The IRS does not know either.
If you call the IRS help line, you often get different answers to the same question.
If you talk to an IRS agent, they often give different answers.
The IRS knows that if Elijah Cummings says "jump" that they must say "how high?"
And, I’ve heard that if you rely on information from an IRS rep on the phone, that you can still be held liable for errors.
I’ve heard that you need to get tax advice/interpretations of laws and regulations, in writing, from the IRS to be able to defend yourself against an audit of certain things. Someone correct me if I’m mistaken in that. If true, it is maddening, because it means you can’t get clarification without jumping through lots of hoops.