What are the tax implications for private stock derivatives in Europe and how do they differ from the US?

I’m not an expert on the derivatives front, but we’ve heard it's very difficult for most employees. 

There are different sets of complications. Depending on the geography you're in and the type of instrument you get from the company you work at, you get taxed either upon the grant, upon vesting, or at exit. You’re taxed differently for each. 

When the taxation happens upon grant or vesting, typically, the company you work for informs you. It doesn't mean that they give you the money or you have the money to actually pay the taxes, but at least they're there to tell you how it should happen.

At the exit, it's not so much the amount of tax that you pay that is problematic for people as much as knowing how to file them and when to pay them. Since it's complicated, most of the employees have no clue how to optimize for it. It's not as obvious as in the U.S. where, you know you can exercise early, then, you pay less taxes at exit. In Europe, it's slightly more complex.

The average European employee is a lot less sophisticated when it comes to approaching their equity than the average U.S. employee. In most startups, the equity's still seen as a lottery ticket/bonus rather than a core part of compensation. So, a lot of the financial instruments that exist in the U.S. for employees to make the most of their equity don't exist at all in Europe. There's no European SecFi or anything like that.