I only take away 1 from their ELO since our ratings are too far apart. It's close to 500.
So, basically, it's the same thing as someone ranked 1800 fighting against 1300.
Edit: So, Vladar messaged me and clarified what he wanted to know. Sorry, I misunderstood. I attacked someone within my range, and although I didn't go up in rating, the person I attacked did lose 1 to their rating.