There's nothing particular unusual about Japan's taxation here. If you buy stock at the stock exchange at $100 and its price increases to $150 but you don't se

There's nothing particular unusual about Japan's taxation here. If you buy stock at the stock exchange at $100 and its price increases to $150 but you don't sell it, you don't pay any taxes. If a company pays you with stock that's worth $100 then you pay income taxes on it (even if you don't sell it), just as if it were salary. It makes sense to me. (If the company bought you a car you'd have to pay taxes on it, even if you didn't sell it; otherwise it would be a great tax loophole.) With stock options it's similar. You don't pay any taxes when the company grants you options or when they vest. If the strike price is $10 and you exercise it when the market price is $100, you pay income taxes on $90 (basically your company paid you $90).