the concept of additional income "push you into a different tax bracket" is a misnomer. Only the income above the bracket line gets taxed at the higher rate. There isn't a reason to avoid getting more income in a given year unless you have a way to defer it (like some retirement accounts allow)
In the context of the article, it makes sense. If you have a choice to sell a bunch of stock on either December 31 or January 1, and selling the stock would put you into a higher tax bracket, it makes sense to sell enough stock on December 31 to "fill up" your earlier year tax bracket, and sell the rest on Jan 1.
Or in a simpler use case, you know one year or the other will be a low income year, you sell the stock in that year.
The context of the article is a tech employee getting ESPPs. Such a person is already nearing the top of the tax bracket anyway. It's at most going to mean two or three percent difference on just the capital gains. This is, for almost everyone, going to be a completely unnoticeable difference in practice.
Let's say you make $100,000 and a whopping $50,000 of it is RSUs and ESPPs. You've been very lucky and the stock portion is now worth $75,000. You sell. Your federal bracket has gone up by 2% and your California bracket has stayed the same. You will owe an additional $500 in taxes. This is just about the worst case scenario where you're not making that much for tech and your comp is exactly on the edge of a tax bracket and your comp is 50% equity and your company went up by 50% since vesting.
Except in reality Jan 1 is always a holiday and Jan 2 is always a volatile trading day, so your tax savings may not be worth the risk of the price swing on the first trading day of the new year.
The thing being disputed isn’t timing etc. it’s the concept of being “pushed into” a tax bracket. In the US at the federal tax level your income is taxed in buckets.
If the brackets are 10,000 @5%; 100,000 @10%, if you make 100,000 your first 10,000 is taxed at 5% and the next 90,000 is taxed at 10%.
Outside of long/short term gains, all things being equal, the timing is not especially important
“However, New York also has a provision called tax-benefit recapture, which essentially turns its progressive tax into a flat tax for high earners, says Eric Bronnenkant, head of tax at Betterment and a certified public accountant.”
I see you made it to the fourth bullet point in the first paragraph of one of the two links.
It actually matters - or can matter, anyway - if you have any event pushing your income above $1M (if filing single) because of the change in deduction treatments.
The actual effect of recapture schemes is to increase marginal tax rates on mid-high incomes while leaving the highest brackets mostly untouched, and then lie about it.
