Originally Posted by MrMuckets
You can only write off gambling losses equal to what you declare as gamblling winnings. So unless you are a professional player it makes no sense to try.
First sentence is true. Second sentence makes no sense at all. Assuming we're talking about US citizens, every person is entitled to right off gambling losses to offset gambling winnings that are declared. It would be insame to have $20,000 in winnings and ignore, for example, $18,000 in losses. Why would you take tax liability on $20K when that can be reduced by losses? The losses have had to happen in the same year that the winnings did and the losses can only be claimed up to the amount of winnings. If you didn't win anything, then no losses can be claimed.
Now, having said that, if you don't have any records then you're probably screwed. Even if it isn't a record from the casino, you can track your wins losses in a notebook or ledger. That will suffice. And no, you don't have to be a pro or filing as one.