There is no set formula either for how much commission is charged or how it is split up-to do so would be called price fixing and a violation of Federal Fair Trade laws. The total amount of commission is derived through negotiation between the seller and their agent and should be based on the amount of work- including advertising, open houses, and negotiation time that will be required to perfect a sale. The portion of that total commission that is offered to co-oping brokers (the buyer's agent aka the selling agent) is also based on an estimate of the amount of labor to bring a specific buyer to the closing table on the subject property.
As for the referral piece there isn;t always a referral involved but if there is it can only be paid to a licensed real estate broker and it is a negotiation between referee and referor. The referral fee is paid by the agent who received the referral. So for example- if I as an agent have a Realtor friend in another state and that Realtor friend has a client who is relocating to my state they might call me and say that want to give me a referral. We would then negotiate what piece of my earned commission I would offer them to send me the person. If they told me the buyer is well qualified, has some source of income or cash to buy the property and has a timeline by which they have to be relocated I might offer a bit more- say 25% of my portion of the commission. On the other hand if my buddy tells me the buyer does't yet have a job in my state, they plan to make multiple trips out to house hunt etc I would most definitely offer less- I would try to offer 15% and probably end up paying 20%. The rationale is buyer number one is motivated and, at least in theory, should not take as long to get the table, Buyer number 2 is going to be more work to get them to purchase a house so I want a bigger piece of the pie because I have to spend more time energy, gas etc to help them.
I hope this helps and makes sense to you
Carole & Greg
Karen Paytas, GRI, CMS
Real Living Kee Realty
That would depend on the agreement between all the Agents. You don't need to worry about it - unless you signed an agreement with your Agent to pay them something over and above what the seller is paying.