I gave my sister permission to claim me on her 2012 tax return but I would only agree if she agreed to give me 3/4 of what I brought to the table, she did agree. Shortly after she kept telling me different reasons they wouldn't do it. Now, since then she and my Mom have slipped and said and done things that point in the direction that they did, in fact claim me. My question; How do I find out if she claimed me? And if so how much did they get under MY name?

Why do you think you would be entitled to any of it?

Why didn't you file for yourself? If your income was low you would usually have gottem more back.

How old are you?

And who supported you for that year?

You find out by filing a tax return for 2012.
You can't find out how much they got (if any) until you are either accepted or denied by the IRS.

How much benefit they got from claiming you depends on your AGE and THEIR marginal tax bracket.

Most likely the benefit is about $500.