Stress
There are two parts to the stress of being what is basically a money cop (which sounds like a movie starring Jackie Chan). Most of your day will be spent in an office, sitting at a desk, going over files and data and transactions and statements and notes and counter-statements ad nauseum. Physical stress will include staying immobile for hours on end, while mental stress includes all those horrible, horrible numbers.
Meanwhile, on the cop side of this B-movie, you've got the stress of enforcing tax law, which is the most unpopular kind of law there is (the most popular kind being JLaw). People who don't want to pay their taxes really don't want to pay their taxes. You'll have to deal with hostile suspects, untrustworthy witnesses, surveillance, and even the occasional shady situation. There's also all the testifying you have to do.
And don't get us started on the paperwork. There will be piles of it. We're talking enough to choke a volcano.