Whether or not you pay tax upon acquisition of your shares depends on your jurisdiction. In the USA, you won't pay capital gains tax until you actually sell the shares (hopefully at a good profit). In Canada, at least when I knew anything about the situation there, people did indeed have to pay capital gains on purchased shares even if they subsequently became worthless. So if you're going to participate in an ESOP (employee stock option plan), be sure to check the tax codes for the country you live in.

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