As I also recall, holding them complicated my taxes that year and put me into AMT threshold. This may have been from option exercise though, I can’t remember.
If you were allowed to sell on the vesting day (open trading window etc) there is generally no way to reduce any tax burden, you are taxed as regular income on the vesting day based on the vesting price, no amount of waiting will reduce your tax liability.
Nearly all the RSU cases I’ve always seen are super simple: on date X, a given amount of shares will be given to you via vesting. You take whatever those shares are worth on that day, and pay regular tax. If you decide to hold past the vesting day, you’ll be subject to additional tax liability if the share price increases, but this additional liability will be $0 if you sell on vest day. It’s completely equivalent to getting just a variable W2 income.
In this simple framework, I’m confused as to what “discounted share price” even means. Certainly for all FAANG and big public companies it works like this.
Sorry for the confusion.