It's very hard to collect the history vesting information, especially the stocks I sold were vested in several years. I cannot find accurate records. So just wonder why I need to provide these information? Will it impact the final tax return amount when I already have 1099B? For RSU, doesn't IRS just care about the cost price and the sold price? I mean, when the stock was vested to me, I believe my employer had withholded the tax from my salary for the cost price.
