Just had a nasty though. Don't tell the tax office about this. They'll could tax you as income on the "New Coin" a.k.a. Ethereum you got for free, and you claim a capital loss on the drop in price of the old coin (Etherium Price - Classic Price). Yikes!
Ethereum -> ETC.
New Coin -> Ethereum.
The market said New Coin a.k.a. Ethereum is worth more. But who cares about fiat, eh?