I filed my federal tax return showing slot machine winnings as income.. I did not offset my winnings with gambling losses that I incurred. The preparer I used told me that in order to offset gambling winnings with gambling losses I must keep a detailed diary of all slot play. The casino where I gambled provides a yearly profit and loss statement. Is my tax preparer correct or can I now amend by return and use the profit and loss statement to show losses that offset my winnings?