Do I have to pay taxes on a Bitcoin investment when I'm withdrawing it to my US bank account before I actually received the money?
You are definitely being scammed - you should write off the $500 as an expensive lesson and never deal with these people again.
No legitimate company operates in such a way. $200 on a $18500 profit is also not what you would pay under any real tax structure, and even if you had to pay it, it would be paid alongside your regular taxes.
Even if the company had to deduct it and file it separately, they could do so by deducting it from the &quot;profits&quot;.
If they had a way to turn $500 into $19000, they wouldn't need $500 from you to do so - they'd already be amongst the richest people in the world.