My $7,500 opinion on the tax law changes:
We are quite deep into the year. Congress takes a week or so hiatus for Turkey Day and, I believe, two weeks for the holidays. Most major tax legislation is usually passed in summer. This timing allows for remedial legislation to be passed that corrects flaws or misstatements in the original law. It also lets the lawyers for Treasury to begin drafting the regs that interpret the law and Congress' intent for those areas that impact most taxpayers. It is really, really difficult to prepare taxes accurately and professionally with new and unfamiliar terms, definitions, scenarios, and the like without regulations to guide us as to how facts, circumstances, and transactions apply to these new laws. Treasury regulations offer a lot of insight until disputes work their way through the court system, which we know can take years and years.
It is true that in prior years there has been tax legislation passed in November or December--even late January a few years back. But most of those bills were extenders of provisions that had sunset dates written into them, not a brand-spanking new Title 26.
I would think that if there were a brand new tax code that the Senate and House will not hammer out a joint bill until late in the first quarter. By then, we will be too deep into the new year to have all the provisions be retroactive to January 1. We taxpayers make our personal, business, and financial decisions daily. Much of the economy would grind to a halt while we sat around waiting for Congress to do something.
If I am right about the timing of the passage, then it would be political suicide for selected provisions like the repeal of the Section 30D credit, among other things, were retroactive to January 1. If this repeal does make it to the President's desk, I could see it repealed effective the day the bill is voted upon, or a date shortly thereafter (like the end of a calendar quarter,) or repealed effective December 31, 2018, for years beginning in 2019.
Take my words with a hefty dose of sodium chloride. I could be w-a-a-a-y wrong.