It is the "when" that I a focusing on here. How long have they known what they will do?
To get closer to ‘when’ and ‘who’:
“Follow the money”
There are even "implementing regulations" that've been drafted and subjected to preliminary review ~ but I'd suspect they're not older than6 months. Right now they are cleaning them up to meld with what looks like the "final" legislative proposal. Some staffer will have the job of tracking changes in the legislation as it's butchered/crafted, and making preliminary changes to the implementing/regulatory rules.
With modern computer systems they can probably stick this stuff together in under a week.
We regularly incorporated new postal rate schedules and rules into the existing rules in 2 or 3 days (with allnighters) and had them out for the 10 day period of notice and comment before the big mailers were aware that they would have to "pay up" sooner than they thought.
I suspect the Treasury guys are as good, as are their counterparts on the committee staffs in Congress.
I used to make 3 or 4 different versions of a proposed rule change and just lay them out on my desk so the corporate spies could come around and get confused ~ I suspect the Treasury and committee staff guys do the same thing. We will be hearing "surprise findings" as this progresses, with instant denials of "That's not in there".
Could be a lot of fun. Insofar as is possible I'll try to give an "insiders view" of apparant problems in drafting law and rules as this proceeds. Some of it's going to be beyond my understanding, but the process of drafting, reviewing, and so forth is fairly cut and dried.