No, you cannot report the loss. Gambling losses are not deductible in any fiscal year. If you win $40 and lose $20 you can report a net $20 in winnings, but not the other way around.
Nightmare scenario: A gambler gets red hot and wins a million dollars in craps on New Years Eve 2013. Wakes up the next day and loses the million.
He owes taxes on the million won in 2013 and gets no write off of the million he lost in 2014. Ouch!
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