Hi.
i didn't traded so much of my crypto for FIAT so i didn't dealt with that question yet.
however i think it's an issue need to be dealt with.
1. do you use accounting services?
2.if so, do you keep documentation of all traded or bought coins?
3. what do you do in cases of profit from ICO's
WHAT SHOULD I DO??
Situation depends on the country you reside. If you want an accurate and more reliable answer, I suggest you specify or tell your country. In my case, because I only encash minimum amount, I usually dont pay tax.