I can declare anything but how will I prove my loss? Screenshots? List of transactions and a statement that the username "btcloser" belongs to me?
It's not that simple. Let's say I buy bitcoins on LocalBitcoins and sell them later for a loss. I declare that loss to IRS - will I be able to deduct that amount from my income? I highly doubt it.
As far as I understand it yes.
I will be doing this exact thing but with gold. I ended up taking a small loss on some gold I bought and then resold.