It depends a lot on the perception you're trying to create. I can't find it now, but there was an article a while back that spoke to the benefits of having a d

It depends a lot on the perception you're trying to create. I can't find it now, but there was an article a while back that spoke to the benefits of having a dedicated identity for your billing department. In short, it helps to separate the you that negotiates contracts and produces from the you that asks for the money. Of course, if you were doing something like this, you would want to make sure you used the plural.