1099G

[Glenndd]

How can you claim gambling losses when a taxpayer is not itemizing?

[sjrcpa]

You can't.

(Unless they are a professional gambler-very few people are)

Your heading says 1099-G. Gambling winnings are reported on W-2G. Maybe you should Edit your post.

[Just-Lisa-Now-]

You can't.  Unless they kept track of gambling sessions and use the gambling per session rule. 

You'll need to do some research as to how that works, most people don't keep track and cant use it.  Im guessing the audit rate may be higher than usual on these types of returns as well.

[taxes96786]

Casinos will issue a win/loss statement that looks like a 1099....you need to input it completely onto the return if you qualify to take the losses.