There are Federal and State laws tthat apply to billing for medical services. In order to bill an insurance carrier on a patient's behalf and/or bill a patient you not only are required to code the services...you are required to keep and have available documentation in support of those services. Operative notes, cardio and pathology reports, etc. are the types of documentation that needs to be kept. Hospitals and providers are reimbursed for their services based on the levels of service provided. The documentation supports the level of services provided by a hospital or a provider (doctors, therapists, nurse practicioners, etc.) to the patient.
CPT (procdure codes) and ICD-9-CM (diagnosis codes) are used by both hospital based and physician based coders, they are applied differently. Medicare has Part A and Part B coverage for services. Part A is for hospital based service and Part B for the provider (physician, non-physician provider) services. Each has it's own rules, regulations, and guidlines on how services and procedures are to be billed and how they get reimbursed.
Simply: Onsite coders are probably the hospital based coders...coding for the services provided by the hospital and it's staff. Offsite coders are probably the ones coding the physician's or other provider's services. It's more complicated than that, but would take a lot more space to explain fully.
At discharge, a patient who was an inpatient will get billed for services provided by the hospital and it's staff. This includes facility charges for use of equipment owned by the hospital, the rooms, operating suites, etc. as well as staff services. A physician who sees a patient at the hospital, perhaps does surgery or another service for the patient would bill his or her services separately from that of the hospital. Due to the different rules and regulations regarding hospital based vs physician based services, the different coders would each need documentation to code for whoemever they represent.
If the patient is a Medicare patient, the bills for the hospital would go to Part A Medicare, while the physcian/provider's charges for services performed would go the Part B Medicare.
Can you talk directly with one of the coders from the group you are doing the software for?
I'm guessing as to what you are looking for...not enough information on exactly what the A and B you're speaking of is. I am thinking they are referring to Medicare Part A aand Medicare Part B. Medicare Part A governs the billing of hospital charges, while part B governs the physician charges. Each has it's own rules and regulations that have to be followed. While basically the codes are the same...the regulations covering their billing differ from Part A to those of Part B. Part A is hospital based billing. Part B is physician based billing.
However, the group you're coding for may have a different "internal"/"specific to their office" meaning for A and/or B.