want to know why sellable is less than vested quantity
Let's say 1 stock = $1 Vested stocks =100 So, you just got granted $100 Now, you gotta pay tax on the $100. So, a number of stocks are withheld and sold to pay the tax you owe. Let's say you are charged with 40% tax i.e you owe $40. Stocks worth $40 are withheld and you receive sellable quantity of 60 stocks.
And for these 60 stocks, we need to pay long term gains tax right when we sell ?
Yes, you pay long term stocks when you hold them for an year or more. Otherwise, short term.
The cost basis for the 60 shares is the vesting price.
withheld for taxes
So if i keep them for long term will the sellable quantity increase? If it matters i dont work for the same company anymore
No, shares are usually sold to cover taxes at the time they vest. That money is gone until tax season, at which point you'll get a small refund if too much was sold.