I have a client who was paid with etherium/crypto for a service. This is my first time working with crypto in general. I've indicated on the 1040 that they have digital currency. I have set up his Schedule C with his total income (which happens to be all from crypto). I have completed his Schedule as usual, but now, my question comes into the "cashing in" of the crypto. I'm guessing this must also be reported on the Schedule D form/8949, correct? If so, how is this not double taxation?

The client did not receive a 1099-NEC from the contractor for his service or a 1099-B for the "sale" of his crypto. 

Finally, do I have to prepare anything else for the crypto currency assets? I thought I read something about the gift tax return, but that doesn't seem right. 

I apologize; I'm new to the crypto thing.

Thanks for your advice in advance.

Devera