Nice to see tax laws for the rich can get passed, but substantive change to do with criminal justice, healthcare etc go nowhere.
The problem this bill targets is the "exercise tax" interaction. Say you are an employee at a start up. Said start up can't afford your full normal salary so they pay you something less but offer you the OPTION of PURCHASING stock in their privately held corporation at a fixed rate (stock options) and often at a "discount" (more on this below).
So a private "board" (of the company) meets and arbitrarily assigns a dollar value to the shares of their company...again this is more or less arbitrary since all stock is privately held so there is no market interaction for price setting. Based on this dollar value, they offer you, the employee, a "discount". So if your board sets a price estimate of $1.50 per share, they might put in your stock option agreement a fixed price of $1.20 per share for X number of shares.
But this means, at least according to tax law, that when you purchase the stock at $1.20, you, the employee, have an IMMEDIATE realized gain of $0.30 per share...lucky you! So this is of course taxable.
Problem being that the current share "value" and the corresponding discount was arbitrarily assigned and actually...you spent $1.20 on a share of a company that has no resale value. So not only do you "buy" (or "invest") into ownership of your start up...you then get taxed on top of it for a "realized gain" that actually doesn't exist. So it's not like you can turn around and sell some of your new "stock" to be able to pay the tax...