I'm not sure you understand my question.
Lets say you transfer a domain name from registrar A to registrar B. It has 10 years registration remaining, at the time it is transferred. Prior to the transfer, registrar A was paid in full and in advance for those 10 Years. After the transfer, registrar B is now responsible (or so it seems) for the costs to carry this name on it's books for those remaining ten years that registrar A actually received advanced payment for. So, what I was curious about is whether registrar B receives any up-front compensation for this. Also whether registrar A has to give some back.