Most billing software packages have a place where you can store the Procedure Code (CPT) and attach a dollar amount to it. Then when you process a fee slip for a given patient, when you type in the CPT code(s), the dollar amount automatically appears.
But, as Michelle stated, you initially get the dollar amounts from your client.
Periodically the carriers will increase the amount paid for a given CPT code, and its easy to miss this unless you are constantly asking the various carriers what their payment amounts are. Therefore, the client will be underpaid until you discover that the payable amount has been increased.
We avoid this by attaching to the various CPT codes in our billing program a dollar amount that is generally 20% or so higher than what the doctor charges (an amount he usually determines by looking at what the carriers will pay for that code). This process requires us to write off a certain amount when processing payments. But, we always capture the increase in payment(s) made by the carriers as soon as they happen. We then change the dollar amount attched to the CPT code(s) in our program to 20% higher than the new payment amount.