Here is joint analysis, penned by David Kamin, regarding the state of the play re. state and local income tax deductions for Trump and law firm partners, but not for you.
Because I'm a gentle and charitable soul, I am open to the theory that the mistakenly low revenue estimate - albeit, apparently reflecting a deliberate choice to retain likely state and local income tax deductibility for business owners and passive investors but no one else - arose innocently. But a lot of foot-dragging seems to have been going on towards the end of preventing its being addressed or corrected. And at this point, even if they do correct it, I for one will be inclined to attribute it to their having decided the game was up. A mere misunderstanding could easily have been fixed as early as Tuesday, three days ago, and it wasn't.
Some people not familiar in detail with the substantive analysis have been skeptical of our conclusion - likely continued state and local income tax deductibility for the favored ones - for a couple of reasons. One has been that, under current law, they are rightly skeptical that the favored ones can deduct state and local income taxes other than as itemized deductions on grounds that are independent of the business/ investment aspect (and that are being repealed). But: this view overlooks (a) the subtle backdoor change to flush language at the end of section 164(a) that supports the result, and (b) the distinguishability of existing case law that arises under a different provision altogether (as discussed in the Kamin post. So their assumption that the only deductions at issue are those from a narrow category of existing state and local taxes, such as NYC's "unincorporated business tax" (UBT) is probably incorrect even as things stand. Plus, as Kamin points out, even under that interpretation states could do a whole lot of self-help to make much of their income taxes effectively deductible at the federal level without significant substantive change to their laws. (And it would be a freebie to their own high-flyers that would come purely at the expense of the federal government, not at the expense of less privileged fellow citizens within their own states.)
Second, they may be relying on language in existing section 164(a) that admittedly is not 100% slam dunk certain to provide the result that we have been arguing is probable. The relevant language refers to taxes "paid or accrued within the taxable year in carrying on a trade or business or an activity described in section 212." One could argue, against our view, that this means the tax has to be imposed directly on the trade or business, etc., in its capacity as such - whence NYC's UBT but not regular income taxes.
Not impossible, but it puts an awful lot of weight on a very particular reading of "in." Note how incredibly easy it would have been to signal, either in the statute or the legislative history, that this meant distinguishing between the individual on the one hand and the business on the other hand (even in the case of a sole proprietorship), such that the tax had to be imposed on the business qua business in order to be deductible. But rather than signaling any such view, either in the statute or the legislative history, we have repeated statements that there will be deductions for state and local taxes, including income taxes, incurred in the trade or business and investment settings.