Yes.

They are only illegal in the following 10 states

Alabama, Alaska, Iowa, Kansas, Louisiana, Mississippi, Missouri, Oklahoma, Oregon, and Tennessee.

Now being from iowa I’m curious what is a buyer rebate? 

 It's when you give part of your commission to the buyer.

Hey @Ken Cai - as far as I'm aware they are, commission rebates can be used by different agents as a means to ensure that the deal gets done in scenarios where the buyer/seller are unhappy with the amount of cash they're having to come up with for closing. 

In my experience, it's not super common as most agents aren't super happy to give up their commission when closing a deal and would rather not work with clients that recommend this early on in the process.

ah, thanks for explaining, I can attest, definitely not legal here in Iowa.  That has to be negotiated with the listing agent. Same result, but a different process.  Although, in my experience agents who discount commissions their own OR the other agent's commission are typically not at the same level of providing service and advice.  I might get some hate, but after a couple of hundred transactions in my short agent career, is VERY transparent, you get what you pay for.