I have a friend who is in the same position as you. There is a difference between being employed and being a contractor. Since you get them in the capacity as a contracting person, they dont count as capital gains, but as ordinary salary when you excerce them where you obviously pay all your social security charges and much higher tax rate. At least thats the case where i live (europe). It is up to you though to declare it correctly. Its also logical as you have to do the same on your invoiced money as well.

I hope i didn't spoil it for you ;)